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All questions of Chemical Reactions and Equations for Class 10 Exam
Which of the following is a combination reaction?- a)CaCO3 → CaO + CO2
- b)H2 + Cl2 → 2HCl
- c)H2CO3 → H2O + CO2
- d)2KClO3 → 2KCl + 3O2
Correct answer is option 'B'. Can you explain this answer?
Which of the following is a combination reaction?
a)
CaCO3 → CaO + CO2
b)
H2 + Cl2 → 2HCl
c)
H2CO3 → H2O + CO2
d)
2KClO3 → 2KCl + 3O2
 | Roshni chauhan answered |
Balanced Equation:
H2 + Cl2 → 2HCl2
H2 + Cl2 → 2HCl2
The above reaction is an example of combination reaction because two different elements are combining to form a single compound.
Which of the following is a decomposition reaction?- a)NaOH + HCl → NaCl + H2O
- b)NH4CNO → H2NCONH2
- c)2KClO3 → 2KCl + 3O2
- d)H2 + I2 → 2HI
Correct answer is option 'C'. Can you explain this answer?
Which of the following is a decomposition reaction?
a)
NaOH + HCl → NaCl + H2O
b)
NH4CNO → H2NCONH2
c)
2KClO3 → 2KCl + 3O2
d)
H2 + I2 → 2HI
 | Meera Rana answered |
A decomposition reaction occurs when one reactant breaks down into two or more products. Examples of decomposition reactions include the breakdown of hydrogen peroxide to water and oxygen, and the breakdown of water to hydrogen and oxygen.
2KClO3 → 2KCl + 3O2
2KClO3 → 2KCl + 3O2
The reaction C + O2 → CO2 + Heat is a:- a)Combination reaction
- b)Oxidation reaction
- c)Exothermic reaction
- d)All of the above
Correct answer is option 'D'. Can you explain this answer?
The reaction C + O2 → CO2 + Heat is a:
a)
Combination reaction
b)
Oxidation reaction
c)
Exothermic reaction
d)
All of the above
 | Amit Sharma answered |
C + O2 → CO2 + Heat
- This is a Combination reaction because C and O2 are combining to produce one single compound CO2.
- This is also an Oxidation reaction because carbon is getting oxidized.
- This is also an exothermic reaction because in this reaction heat is getting released.
So Option D is correct
Which one of the following will be required to identify the gas evolved when diluted HCl reacts with zinc metal?- a)Red litmus solution
- b)Lime water
- c)A burning splinter
- d)Blue litmus solution
Correct answer is option 'C'. Can you explain this answer?
Which one of the following will be required to identify the gas evolved when diluted HCl reacts with zinc metal?
a)
Red litmus solution
b)
Lime water
c)
A burning splinter
d)
Blue litmus solution
 | Kiran Mehta answered |
A burning splinter since hydrogen gas burns with a pop sound.
Zinc being an active metal readily reacts with hydrochloric acid at room temperature to form soluble zinc chloride and hydrogen.
Zn + 2HCl → ZnCl2 + H2.
Fe2O3 + 2Al → Al2O3 + 2Fe
The above reaction is an example of a:- a)Decomposition reaction
- b)Combination reaction
- c)Displacement reaction
- d)Single displacement reaction
Correct answer is option 'C'. Can you explain this answer?
Fe2O3 + 2Al → Al2O3 + 2Fe
The above reaction is an example of a:
The above reaction is an example of a:
a)
Decomposition reaction
b)
Combination reaction
c)
Displacement reaction
d)
Single displacement reaction
 | Anushka Chopra answered |
The given equation is a displacement reaction in which Fe of Fe2O3 has been displaced by Al. Hence, (c) is the correct option.
Can you explain the answer of this question below:ANa+BH2O→CNaOH+DH2 . What would come in place of A , B C and D to balance the equation
- A:
A = 1, B = 1, C = 2, D = 1
- B:
A = 2, B = 2, C = 2, D = 1
- C:
A = 2, B = 1, C = 2, D = 1
- D:
none of these
The answer is b.
ANa+BH2O→CNaOH+DH2 . What would come in place of A , B C and D to balance the equation
A = 1, B = 1, C = 2, D = 1
A = 2, B = 2, C = 2, D = 1
A = 2, B = 1, C = 2, D = 1
none of these
 | Shweta singh answered |
2 Na + 2H2O gives 2NaOH + H2
So option B is Correct answer.
Which of the following is a displacement reaction?- a)CaCO3 → CaO + CO2
- b)CaO + 2HCl → CaCl2 + H2O
- c)Fe + CuSO4 → FeSO4 + Cu
- d)NaOH + HCl → NaCl + H2O
Correct answer is option 'C'. Can you explain this answer?
Which of the following is a displacement reaction?
a)
CaCO3 → CaO + CO2
b)
CaO + 2HCl → CaCl2 + H2O
c)
Fe + CuSO4 → FeSO4 + Cu
d)
NaOH + HCl → NaCl + H2O
 | Gaurav Kumar answered |
Fe + CuSo4 → FeSO4 + Cu
is displacement reaction.
In these reaction iron (Fe) displace copper (Cu)
Hence, it is a displacement type of reaction.
is displacement reaction.
In these reaction iron (Fe) displace copper (Cu)
Hence, it is a displacement type of reaction.
(a) is a decomposition reaction.
(b) and (d) are neutralisation reactions.
(b) and (d) are neutralisation reactions.
Which of the following is an example of displacement reaction?- a)4 Na+ O2 → 2 Na2O
- b)2 Cu + O2 → 2 CuO
- c)Mg + 2 HCl → MgCl2 + H2
- d)N2 + 3 H2 → 2 NH3
Correct answer is option 'C'. Can you explain this answer?
Which of the following is an example of displacement reaction?
a)
4 Na+ O2 → 2 Na2O
b)
2 Cu + O2 → 2 CuO
c)
Mg + 2 HCl → MgCl2 + H2
d)
N2 + 3 H2 → 2 NH3
 | Orion Classes answered |
It is a single replacement reaction.
Mg + 2HCl → MgCl2 + H2
Mg + 2HCl → MgCl2 + H2
Which of the following metals comes above zinc in reactivity series?- a)Silver
- b)Copper
- c)Aluminium
- d)Iron
Correct answer is option 'C'. Can you explain this answer?
Which of the following metals comes above zinc in reactivity series?
a)
Silver
b)
Copper
c)
Aluminium
d)
Iron
| | Karthik murthy answered |
Reactivity Series:
The reactivity series is a list of metals arranged in order of their decreasing reactivity. The most reactive metal is placed at the top and the least reactive metal is placed at the bottom of the series.
The reactivity series of metals is as follows:
Potassium > Sodium > Calcium > Magnesium > Aluminium > Zinc > Iron > Lead > Copper > Silver > Gold
Explanation:
Aluminium is more reactive than zinc and is placed above zinc in the reactivity series. This is because aluminium has a stronger tendency than zinc to lose electrons and form positive ions.
When aluminium is exposed to air, it reacts with oxygen to form a layer of aluminium oxide. This layer of oxide is very thin and is also very stable. It prevents further reaction of aluminium with oxygen and protects the metal from corrosion.
Zinc, on the other hand, reacts with oxygen in the air to form zinc oxide. However, the layer of oxide formed on zinc is not as stable as the layer of oxide formed on aluminium. Therefore, zinc is more susceptible to corrosion than aluminium.
Conclusion:
In conclusion, aluminium is more reactive than zinc and is placed above zinc in the reactivity series. This means that aluminium can displace zinc from its compounds in a chemical reaction, but zinc cannot displace aluminium from its compounds.
The reactivity series is a list of metals arranged in order of their decreasing reactivity. The most reactive metal is placed at the top and the least reactive metal is placed at the bottom of the series.
The reactivity series of metals is as follows:
Potassium > Sodium > Calcium > Magnesium > Aluminium > Zinc > Iron > Lead > Copper > Silver > Gold
Explanation:
Aluminium is more reactive than zinc and is placed above zinc in the reactivity series. This is because aluminium has a stronger tendency than zinc to lose electrons and form positive ions.
When aluminium is exposed to air, it reacts with oxygen to form a layer of aluminium oxide. This layer of oxide is very thin and is also very stable. It prevents further reaction of aluminium with oxygen and protects the metal from corrosion.
Zinc, on the other hand, reacts with oxygen in the air to form zinc oxide. However, the layer of oxide formed on zinc is not as stable as the layer of oxide formed on aluminium. Therefore, zinc is more susceptible to corrosion than aluminium.
Conclusion:
In conclusion, aluminium is more reactive than zinc and is placed above zinc in the reactivity series. This means that aluminium can displace zinc from its compounds in a chemical reaction, but zinc cannot displace aluminium from its compounds.
The reaction H2 + Cl2 → 2HCl is a –- a)Decomposition reaction
- b)Combination reaction
- c)Double displacement reaction
- d)Displacement reaction
Correct answer is option 'B'. Can you explain this answer?
The reaction H2 + Cl2 → 2HCl is a –
a)
Decomposition reaction
b)
Combination reaction
c)
Double displacement reaction
d)
Displacement reaction
| | Anjana Khatri answered |
It is a reaction in which two substances react with each other to make a single substance. Therefore, H2 + CL2 = 2HCL is an COMBINATION REACTION. It is a special case of addition reaction known as synthesis.
In reaction SO2 + 2H2S → 2H2O + 3S, the reducing agent is- a)SO2
- b)H2S
- c)H2O
- d)S
Correct answer is option 'B'. Can you explain this answer?
In reaction SO2 + 2H2S → 2H2O + 3S, the reducing agent is
a)
SO2
b)
H2S
c)
H2O
d)
S
 | Raghav Bansal answered |
- In the reaction SO2 is getting reduced to S as oxygen is being removed.
- Similarly, H2S is oxidised to S as hydrogen is removed.
- The species getting oxidised facilitates the reduction process and is the reducing agent.
- Hence, H2S is the reducing agent and Oxidising agent is SO2.
So, option B is correct
Which of the following represent a double displacement reaction?- a)2H2 + O2 → 2H2O
- b)2Mg + O2 → 2MgO
- c)AgNO3 + NaCl → AgCl
+ NaNO3 - d)H2 + Cl2 → 2HCl
Correct answer is option 'C'. Can you explain this answer?
Which of the following represent a double displacement reaction?
a)
2H2 + O2 → 2H2O
b)
2Mg + O2 → 2MgO
c)
AgNO3 + NaCl → AgCl + NaNO3
+ NaNO3d)
H2 + Cl2 → 2HCl
 | Environment Lover answered |
Yah the correct answer is c as it follow the definition of displacement reaction
The colour of zinc metal is- a)reddish-brown
- b)grey
- c)Blue
- d)silvery-white
Correct answer is option 'D'. Can you explain this answer?
The colour of zinc metal is
a)
reddish-brown
b)
grey
c)
Blue
d)
silvery-white
 | Vikas Kumar answered |
The correct option is D
silvery-white
Explanation for correct option
(D) The color of Zinc metal is silvery.
- An electron gets excited to a higher energy orbital from a lower energy d orbital. The frequency of light absorbed is proportional to the excitation energy.
- This frequency is usually in the visible range.
- The color seen corresponds to the complementary color of the light absorbed.
- Zinc (Zn) is a silvery-white metal.
Hence, option (D) is correct. The color of Zinc metal is silvery.
Which of the following is not an example of chemical change?- a)rusting of iron
- b)milk changes to curd
- c)digestion of food in our body
- d)changing of water to water vapour
Correct answer is option 'D'. Can you explain this answer?
Which of the following is not an example of chemical change?
a)
rusting of iron
b)
milk changes to curd
c)
digestion of food in our body
d)
changing of water to water vapour
| | Amit Sharma answered |
The process of changing water vapour into water is called condensation. It is not a chemical reaction.
When milk converts in curd the process is irreversible and a new substance with different properties is formed hence it is an example of a chemical change.
Rusting of iron is also a chemical change.
What happens when dil hydrochloric acid is added to iron fillings?- a)Hydrogen gas and Iron chloride are produced
- b)Chlorine gas and Iron hydroxide are produced
- c)NO reaction takes place
- d)Iron salt and water are produced
Correct answer is option 'A'. Can you explain this answer?
What happens when dil hydrochloric acid is added to iron fillings?
a)
Hydrogen gas and Iron chloride are produced
b)
Chlorine gas and Iron hydroxide are produced
c)
NO reaction takes place
d)
Iron salt and water are produced
| | Amit Sharma answered |
- Hydrogen gas and iron chloride are produced.
Fe + HCl → FeCl2 + H2
- The iron displaces hydrogen from hydrochloric acid to form iron (II) chloride & hydrogen gas. This is a single displacement reaction.
- Thus the answer is option (A) Hydrogen gas and iron chloride are produced.
The reaction, Zn + 2HCl → ZnCl2 + H2 is an example of:- a)Displacement reaction
- b)Combination reaction
- c)Double displacement reaction
- d)Decomposition reaction
Correct answer is option 'A'. Can you explain this answer?
The reaction, Zn + 2HCl → ZnCl2 + H2 is an example of:
a)
Displacement reaction
b)
Combination reaction
c)
Double displacement reaction
d)
Decomposition reaction
 | Neha Patel answered |
This is a metal/acid reaction if carried out in aqueous solution.
It is also a displacement reaction where 1 atom of Zinc displaces 2 H+ ions
and it is a redox reaction as the Zn atom loses electrons (it is OXIDISED) and the 2 H+ ions gain electrons (they are REDUCED)
An element X on exposure to moist air turns reddish-brown and a new compound Y is formed. The substance X and Y are- a)X = Fe, Y = Fe2O3
- b)X = Ag, Y = Ag2S
- c)X = Cu, Y = CuO
- d)X = Al, Y = Al2O3
Correct answer is option 'A'. Can you explain this answer?
An element X on exposure to moist air turns reddish-brown and a new compound Y is formed. The substance X and Y are
a)
X = Fe, Y = Fe2O3
b)
X = Ag, Y = Ag2S
c)
X = Cu, Y = CuO
d)
X = Al, Y = Al2O3
| | Suresh Reddy answered |
An element X exposure to moist air, forms a reddish brown and a new compound Y is formed.
Fe + H2O +O2 → Fe2 O3
This Fe2O3 is the reddish brown compound which is called rust.
So , X → Fe
Y → Fe2O3
Fe + H2O +O2 → Fe2 O3
This Fe2O3 is the reddish brown compound which is called rust.
So , X → Fe
Y → Fe2O3
So Option A is correct
Which of the following statement is incorrect?- a)In oxidation, oxygen in added to a substance.
- b)In reduction, Hydrogen is added to a substance.
- c)Oxidizing agent is oxidized.
- d)Reducing agent is oxidized
Correct answer is option 'C'. Can you explain this answer?
Which of the following statement is incorrect?
a)
In oxidation, oxygen in added to a substance.
b)
In reduction, Hydrogen is added to a substance.
c)
Oxidizing agent is oxidized.
d)
Reducing agent is oxidized
 | Nk Classes answered |
- a) In oxidation, oxygen is added to a substance: This is correct. Oxidation involves the addition of oxygen or the loss of electrons.
- b) In reduction, hydrogen is added to a substance: This is correct. Reduction typically involves the addition of hydrogen or the gain of electrons.
- c) Oxidizing agent is oxidized: This is incorrect. The oxidizing agent is actually reduced as it gains electrons during the reaction, thereby oxidising the other substance.
- d) Reducing agent is oxidized: This is correct. The reducing agent loses electrons (is oxidized) while it reduces the other substance by donating electrons.
The reaction between lead nitrate and potassium iodide is an example of _______ .- a)decomposition reaction
- b)double displacement reaction
- c)combustion reaction
- d)combination reaction
Correct answer is option 'B'. Can you explain this answer?
The reaction between lead nitrate and potassium iodide is an example of _______ .
a)
decomposition reaction
b)
double displacement reaction
c)
combustion reaction
d)
combination reaction
 | Subset Academy answered |
Lead nitrate reacts with Potassium iodide to form Lead iodide and Potassium nitrate.
Pb(NO3)2 + 2KI → PbI2 + 2KNO3
In reaction SO2 + 2H2S → 2H2O + 3S the reducing agent is –- a)SO2
- b)H2S
- c)H2O
- d)S
Correct answer is option 'B'. Can you explain this answer?
In reaction SO2 + 2H2S → 2H2O + 3S the reducing agent is –
a)
SO2
b)
H2S
c)
H2O
d)
S
 | Navya Patel answered |
In the reaction SO2 is reduced to S as oxygen is removed.
H2S is oxidised to S as hydrogen is removed.
H2S is oxidised to S as hydrogen is removed.
The species getting oxidised facilitates the reduction process and is the reducing agent.
Hence, H2S is the reducing agent and Oxidising agent is SO2.
The given reaction indicates that:
Cu + 2AgNO3 → Cu(NO3)2 + 2Ag- a)Copper is more reactive than silver.
- b)Silver is more reactive than copper.
- c)Both are equally reactive.
- d)None of these
Correct answer is option 'A'. Can you explain this answer?
The given reaction indicates that:
Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
a)
Copper is more reactive than silver.
b)
Silver is more reactive than copper.
c)
Both are equally reactive.
d)
None of these
| | Malini sharma answered |
Explanation:
The given reaction is: Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
This reaction involves the displacement of silver from its compound (AgNO3) by copper. This type of reaction is known as a single displacement reaction or a substitution reaction.
To determine which metal is more reactive, we need to look at the activity series of metals. This series arranges metals in order of their reactivity, with the most reactive metals at the top and the least reactive at the bottom.
Copper is placed below silver in the activity series, which means that silver is more reactive than copper. Therefore, when copper is added to silver nitrate solution, it displaces the silver from its compound and forms copper nitrate. The displaced silver ions combine with copper atoms to form solid silver, which is observed as a brownish precipitate.
Hence, the correct option is A - Copper is more reactive than silver.
The given reaction is: Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
This reaction involves the displacement of silver from its compound (AgNO3) by copper. This type of reaction is known as a single displacement reaction or a substitution reaction.
To determine which metal is more reactive, we need to look at the activity series of metals. This series arranges metals in order of their reactivity, with the most reactive metals at the top and the least reactive at the bottom.
Copper is placed below silver in the activity series, which means that silver is more reactive than copper. Therefore, when copper is added to silver nitrate solution, it displaces the silver from its compound and forms copper nitrate. The displaced silver ions combine with copper atoms to form solid silver, which is observed as a brownish precipitate.
Hence, the correct option is A - Copper is more reactive than silver.
Which of the following is not a physical change ?- a)Boiling of water to give water vapour
- b)Melting of ice to give water
- c)Dissolution of salt in water
- d)Combustion of liquefied petroleum Gas (LPG)
Correct answer is option 'D'. Can you explain this answer?
Which of the following is not a physical change ?
a)
Boiling of water to give water vapour
b)
Melting of ice to give water
c)
Dissolution of salt in water
d)
Combustion of liquefied petroleum Gas (LPG)
| | Aarav agarwal answered |
Physical and Chemical Changes
Physical changes are reversible changes that do not involve a change in the chemical composition of a substance. Examples of physical changes include changes in state (solid, liquid, gas), changes in shape or size, and changes in color or texture. In contrast, chemical changes involve a change in the chemical composition of a substance, resulting in the formation of a new substance(s) with different properties.
Explanation
Of the given options, option 'D' - combustion of liquefied petroleum gas (LPG) is not a physical change. Combustion is a chemical change that involves the reaction of a fuel (LPG in this case) with oxygen in the air, producing heat and light energy. The products of the combustion of LPG are carbon dioxide and water vapor, which are different from the original fuel.
On the other hand, boiling of water to give water vapor, melting of ice to give water, and dissolution of salt in water are all physical changes. In these processes, no new substances are formed, and the original substance(s) retain their chemical composition.
Conclusion
In summary, physical changes are characterized by the absence of a chemical reaction, and the original substance(s) retain their chemical composition. Option 'D' is the correct answer as it represents combustion, which is a chemical change that involves the formation of new substances with different properties.
Physical changes are reversible changes that do not involve a change in the chemical composition of a substance. Examples of physical changes include changes in state (solid, liquid, gas), changes in shape or size, and changes in color or texture. In contrast, chemical changes involve a change in the chemical composition of a substance, resulting in the formation of a new substance(s) with different properties.
Explanation
Of the given options, option 'D' - combustion of liquefied petroleum gas (LPG) is not a physical change. Combustion is a chemical change that involves the reaction of a fuel (LPG in this case) with oxygen in the air, producing heat and light energy. The products of the combustion of LPG are carbon dioxide and water vapor, which are different from the original fuel.
On the other hand, boiling of water to give water vapor, melting of ice to give water, and dissolution of salt in water are all physical changes. In these processes, no new substances are formed, and the original substance(s) retain their chemical composition.
Conclusion
In summary, physical changes are characterized by the absence of a chemical reaction, and the original substance(s) retain their chemical composition. Option 'D' is the correct answer as it represents combustion, which is a chemical change that involves the formation of new substances with different properties.
A balanced chemical equation is in accordance with which one of the following laws given below- a)Law of constant proportion
- b)Law of conservation of energy
- c)Law of conservation of mass
- d)Low of multiple proportion
Correct answer is option 'C'. Can you explain this answer?
A balanced chemical equation is in accordance with which one of the following laws given below
a)
Law of constant proportion
b)
Law of conservation of energy
c)
Law of conservation of mass
d)
Low of multiple proportion
| | Maitri Daga answered |
Answer C
its absolutely correct
its absolutely correct
When ferrous sulphate crystals are strongly heated, the gas/vapour not evolved are of- a)SO2
- b)SO3
- c)O2
- d)H2O
Correct answer is option 'C'. Can you explain this answer?
When ferrous sulphate crystals are strongly heated, the gas/vapour not evolved are of
a)
SO2
b)
SO3
c)
O2
d)
H2O
 | Manish iyer answered |
Heating Ferrous Sulphate Crystals
Ferrous sulphate crystals have the chemical formula FeSO4·7H2O. When these crystals are strongly heated, they undergo a decomposition reaction, breaking down into different compounds.
Decomposition Reaction
The decomposition reaction of ferrous sulphate crystals is as follows:
FeSO4·7H2O(s) → Fe2O3(s) + SO3(g) + H2O(g)
According to this reaction, the ferrous sulphate crystals break down into solid iron(III) oxide (Fe2O3), gaseous sulphur trioxide (SO3), and water vapor (H2O).
Evolved Gas/Vapour
The question asks us to identify the gas/vapour that is not evolved during the heating process. From the above reaction, we can see that three different compounds are produced when ferrous sulphate crystals are strongly heated. These are:
- Iron(III) oxide (Fe2O3)
- Sulphur trioxide (SO3)
- Water vapor (H2O)
Out of these three compounds, only one is not a gas/vapour. That compound is iron(III) oxide (Fe2O3).
Therefore, the correct answer to the question is option 'C', which is O2. This is not one of the compounds produced during the heating of ferrous sulphate crystals, and hence it is not the gas/vapour that is not evolved.
Ferrous sulphate crystals have the chemical formula FeSO4·7H2O. When these crystals are strongly heated, they undergo a decomposition reaction, breaking down into different compounds.
Decomposition Reaction
The decomposition reaction of ferrous sulphate crystals is as follows:
FeSO4·7H2O(s) → Fe2O3(s) + SO3(g) + H2O(g)
According to this reaction, the ferrous sulphate crystals break down into solid iron(III) oxide (Fe2O3), gaseous sulphur trioxide (SO3), and water vapor (H2O).
Evolved Gas/Vapour
The question asks us to identify the gas/vapour that is not evolved during the heating process. From the above reaction, we can see that three different compounds are produced when ferrous sulphate crystals are strongly heated. These are:
- Iron(III) oxide (Fe2O3)
- Sulphur trioxide (SO3)
- Water vapor (H2O)
Out of these three compounds, only one is not a gas/vapour. That compound is iron(III) oxide (Fe2O3).
Therefore, the correct answer to the question is option 'C', which is O2. This is not one of the compounds produced during the heating of ferrous sulphate crystals, and hence it is not the gas/vapour that is not evolved.
Choose the correctly matched pair:- a)CaO + H₂O → Ca(OH)₂ + Heat - Combination Reaction
- b)Fe + 4H₂O → Fe₃O₄ + 4H₂ - Decomposition Reaction
- c)3Fe + 4H₂O → Fe₃O₄ + 4H₂ - Combination Reaction
- d)CO + 2H₂ → CH₃OH - Displacement Reaction
Correct answer is option 'A'. Can you explain this answer?
Choose the correctly matched pair:
a)
CaO + H₂O → Ca(OH)₂ + Heat - Combination Reaction
b)
Fe + 4H₂O → Fe₃O₄ + 4H₂ - Decomposition Reaction
c)
3Fe + 4H₂O → Fe₃O₄ + 4H₂ - Combination Reaction
d)
CO + 2H₂ → CH₃OH - Displacement Reaction
 | Lakesway Classes answered |
- Option A: CaO + H₂O → Ca(OH)₂ + Heat - This is correctly matched as a Combination Reaction. In this reaction, calcium oxide (CaO) reacts with water (H₂O) to form calcium hydroxide (Ca(OH)₂) and releases heat. This is a classic example of a combination reaction where two or more substances combine to form a single product.
- Option B: Fe + 4H₂O → Fe₃O₄ + 4H₂ - This reaction is incorrectly labeled as a Decomposition Reaction. It is actually a redox reaction involving the oxidation of iron and the reduction of water.
- Option C: 3Fe + 4H₂O → Fe₃O₄ + 4H₂ - This is also incorrectly labeled. Although there is a combination of elements involved, it is best described as a redox reaction rather than a simple Decomposition reaction.
- Option D: CO + 2H₂ → CH₃OH - This is incorrectly matched as a Displacement Reaction. It is actually a synthesis reaction where carbon monoxide (CO) and hydrogen (H₂) combine to form methanol (CH₃OH).
Which one of the following is not a chemical change?- a)Cooking of food
- b)Evaporation of water
- c)Burning of candle wax
- d)Digestion of food in our body
Correct answer is option 'B'. Can you explain this answer?
Which one of the following is not a chemical change?
a)
Cooking of food
b)
Evaporation of water
c)
Burning of candle wax
d)
Digestion of food in our body
| | Sarangi rao answered |
Chemical and Physical Changes
Chemical changes involve the formation of new substances with different chemical properties, while physical changes involve changes in the physical state or appearance of a substance without changing its chemical composition.
Cooking of Food
Cooking of food involves chemical changes, as the heat and other ingredients cause chemical reactions that alter the taste, texture, and nutritional value of the food.
Evaporation of Water
Evaporation of water is a physical change, as it involves the change of water from a liquid to a gas without any change in its chemical composition.
Burning of Candle Wax
Burning of candle wax is a chemical change, as the heat and oxygen cause the wax to react and form new compounds such as carbon dioxide and water.
Digestion of Food in our Body
Digestion of food in our body involves chemical changes, as the enzymes in our digestive system break down the food into simpler substances that can be used by our body for energy and growth.
Conclusion
Therefore, the correct answer is option B - Evaporation of water, as it is a physical change and does not involve any chemical reactions or the formation of new substances.
Chemical changes involve the formation of new substances with different chemical properties, while physical changes involve changes in the physical state or appearance of a substance without changing its chemical composition.
Cooking of Food
Cooking of food involves chemical changes, as the heat and other ingredients cause chemical reactions that alter the taste, texture, and nutritional value of the food.
Evaporation of Water
Evaporation of water is a physical change, as it involves the change of water from a liquid to a gas without any change in its chemical composition.
Burning of Candle Wax
Burning of candle wax is a chemical change, as the heat and oxygen cause the wax to react and form new compounds such as carbon dioxide and water.
Digestion of Food in our Body
Digestion of food in our body involves chemical changes, as the enzymes in our digestive system break down the food into simpler substances that can be used by our body for energy and growth.
Conclusion
Therefore, the correct answer is option B - Evaporation of water, as it is a physical change and does not involve any chemical reactions or the formation of new substances.
What type of reaction is characterized by the formation of a single product from two or more reactants?- a)Combination Reaction
- b)Decomposition Reaction
- c)Displacement Reaction
- d)Double Displacement Reaction
Correct answer is option 'A'. Can you explain this answer?
What type of reaction is characterized by the formation of a single product from two or more reactants?
a)
Combination Reaction
b)
Decomposition Reaction
c)
Displacement Reaction
d)
Double Displacement Reaction
| | Lakesway Classes answered |
In a combination reaction, multiple reactants combine to form a single product. An example is the reaction between calcium oxide and water to produce calcium hydroxide. This type of reaction involves the synthesis of a new compound from the combining of elements or compounds.
Which of the following is a balanced chemical equation?- a)H₂ + O₂ → H₂O
- b)2H₂ + O₂ → H₂O
- c)H₂ + 2O₂ → H₂O
- d) 2H₂ + O₂ → 2H₂O
Correct answer is option 'D'. Can you explain this answer?
Which of the following is a balanced chemical equation?
a)
H₂ + O₂ → H₂O
b)
2H₂ + O₂ → H₂O
c)
H₂ + 2O₂ → H₂O
d)
2H₂ + O₂ → 2H₂O
| | Lakesway Classes answered |
2H2 + O2 → 2H2O
The balanced chemical equation is:
- 2 molecules of hydrogen gas (H2) react with 1 molecule of oxygen gas (O2).
- This produces 2 molecules of water (H2O).
- Each side of the equation has 4 hydrogen atoms and 2 oxygen atoms, ensuring mass conservation.
Choose the correctly matched pair.- a)Burning of coal - C(s) + O2(g) → CO(g)
- b)Formation of water - 2H2(g) + O2(g) → 2H2O2(l)
- c)Respiration - C6H12O6(aq) + 6O2(aq) → 6CO2(aq) + 6H2O2(l) + energy
- d)Whitewashing reaction - Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)
Correct answer is option 'D'. Can you explain this answer?
Choose the correctly matched pair.
a)
Burning of coal - C(s) + O2(g) → CO(g)
b)
Formation of water - 2H2(g) + O2(g) → 2H2O2(l)
c)
Respiration - C6H12O6(aq) + 6O2(aq) → 6CO2(aq) + 6H2O2(l) + energy
d)
Whitewashing reaction - Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)
| | Lakesway Classes answered |
- Let's analyze each option to determine the correctly matched pair:
- Option A: (a) Burning of coal - C(s) + O2(g) → CO2(g)
- This is a correct chemical equation for the burning of coal, which is a combination reaction. However, let's verify the other options before concluding.
- Option B: (b) Formation of water - 2H2(g) + O2(g) → 2H2O(l)
- This is also a correct chemical equation for the formation of water from hydrogen and oxygen, which is another example of a combination reaction. We need to check the remaining options as well.
- Option C: (c) Respiration - C6H12O6(aq) + 6O2(aq) → 6CO2(aq) + 6H2O(l) + energy
- This equation correctly represents the process of respiration, an exothermic reaction where glucose reacts with oxygen to produce carbon dioxide, water, and energy.
- Option D: (d) Whitewashing reaction - Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)
- This is the correct chemical equation for the whitewashing reaction. When calcium hydroxide reacts with carbon dioxide, it forms calcium carbonate (which gives a shiny finish on walls) and water.
- All options are correctly matched pairs, but the question asks for one correctly matched pair. Therefore, Option D is chosen as it represents a familiar and specific application that students are likely to recognize easily.
A dilute ferrous sulphate solution was added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?- a)KMnO4 is an oxidising agent, it oxidises FeSO4
- b)FeSO4 acts an oxidising agent and oxidises KMnO4
- c)KMnO4 is an unstable compound and decomposes in presence of FeSO4 to a colourless compound
- d)The colour disappears due to the dilution : no reaction is involved
Correct answer is option 'A'. Can you explain this answer?
A dilute ferrous sulphate solution was added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?
a)
KMnO4 is an oxidising agent, it oxidises FeSO4
b)
FeSO4 acts an oxidising agent and oxidises KMnO4
c)
KMnO4 is an unstable compound and decomposes in presence of FeSO4 to a colourless compound
d)
The colour disappears due to the dilution : no reaction is involved
 | Priyanka Kapoor answered |
In this reaction, potassium permanganate (KMnO4) is an oxidizing agent. It oxidises ferrous sulphate to ferric sulphate in the presence of dilute H2SO4.
2KMNO4 + 10FeSO4 + 8H2SO4 → K2SO4 + 2MnSO4 + 5Fe(SO4)3 + 8H2O
The solution is coloured purple because of the KMnO4 and it eventually disappears when all the KMnO4 in the solution is utilized.
2KMNO4 + 10FeSO4 + 8H2SO4 → K2SO4 + 2MnSO4 + 5Fe(SO4)3 + 8H2O
The solution is coloured purple because of the KMnO4 and it eventually disappears when all the KMnO4 in the solution is utilized.
When Iron nails are added to an aqueous solution of copper sulphate, a chemical change occurs, which of the following is NOT true about this reaction?- a)Blue colour of the solution fades.
- b)Iron nails become brownish in colour.
- c)It is a displacement reaction.
- d)Blue colour of the solution does not fades.
Correct answer is option 'D'. Can you explain this answer?
When Iron nails are added to an aqueous solution of copper sulphate, a chemical change occurs, which of the following is NOT true about this reaction?
a)
Blue colour of the solution fades.
b)
Iron nails become brownish in colour.
c)
It is a displacement reaction.
d)
Blue colour of the solution does not fades.
 | Poonam gupta answered |
Understanding the Reaction
When iron nails are placed in an aqueous solution of copper sulfate (CuSO4), a chemical reaction occurs. This is an example of a displacement reaction where iron (Fe) displaces copper (Cu) from copper sulfate.
Key Points about the Reaction
- Displacement Reaction:
- Iron is more reactive than copper, thus it displaces copper from the solution.
- Color Change:
- The original blue color of the copper sulfate solution fades due to the formation of iron sulfate (FeSO4), which is colorless.
Why Option D is Incorrect
- Blue Color Fades:
- When iron nails are introduced, the blue color of the copper sulfate solution does fade, confirming that copper ions are being replaced by iron ions.
- Brownish Color of Iron Nails:
- As copper is deposited on the iron nails, they turn brownish in color, indicating the presence of metallic copper.
Conclusion
Thus, the statement in option D, "Blue color of the solution does not fade," is incorrect. The blue color does indeed fade as a result of the displacement reaction, making option D the correct choice for what is NOT true about this reaction.
When iron nails are placed in an aqueous solution of copper sulfate (CuSO4), a chemical reaction occurs. This is an example of a displacement reaction where iron (Fe) displaces copper (Cu) from copper sulfate.
Key Points about the Reaction
- Displacement Reaction:
- Iron is more reactive than copper, thus it displaces copper from the solution.
- Color Change:
- The original blue color of the copper sulfate solution fades due to the formation of iron sulfate (FeSO4), which is colorless.
Why Option D is Incorrect
- Blue Color Fades:
- When iron nails are introduced, the blue color of the copper sulfate solution does fade, confirming that copper ions are being replaced by iron ions.
- Brownish Color of Iron Nails:
- As copper is deposited on the iron nails, they turn brownish in color, indicating the presence of metallic copper.
Conclusion
Thus, the statement in option D, "Blue color of the solution does not fade," is incorrect. The blue color does indeed fade as a result of the displacement reaction, making option D the correct choice for what is NOT true about this reaction.
Identify the substances that are oxidised in the following reactions.
2PbO + C → 2Pb + CO2- a)Pb
- b)C
- c)PbO
- d)CO2
Correct answer is option 'B'. Can you explain this answer?
Identify the substances that are oxidised in the following reactions.
2PbO + C → 2Pb + CO2
2PbO + C → 2Pb + CO2
a)
Pb
b)
C
c)
PbO
d)
CO2
| | Shruti menon answered |
Understanding Oxidation in the Reaction
In the reaction:
2PbO + C → 2Pb + CO2, we need to identify which substance is being oxidised.
Oxidation and Reduction Basics
- Oxidation refers to the loss of electrons or an increase in oxidation state by a substance during a chemical reaction.
- Reduction is the gain of electrons or a decrease in oxidation state.
Analyzing the Reaction
1. Lead(II) Oxide (PbO):
- In this reaction, PbO is reduced to lead (Pb).
- The oxidation state of lead decreases from +2 in PbO to 0 in elemental Pb.
2. Carbon (C):
- Carbon is oxidised to carbon dioxide (CO2).
- The oxidation state of carbon increases from 0 in elemental C to +4 in CO2.
Identifying the Substance Being Oxidised
- In this specific reaction, carbon (C) is the substance that undergoes oxidation.
- It loses electrons and its oxidation state increases, making carbon the reducing agent.
Conclusion
- Therefore, the correct answer is option 'B' (C), as it is the substance that is oxidised in this reaction.
By understanding the changes in oxidation states, we can clearly see that carbon is the oxidised component, while lead oxide is reduced.
In the reaction:
2PbO + C → 2Pb + CO2, we need to identify which substance is being oxidised.
Oxidation and Reduction Basics
- Oxidation refers to the loss of electrons or an increase in oxidation state by a substance during a chemical reaction.
- Reduction is the gain of electrons or a decrease in oxidation state.
Analyzing the Reaction
1. Lead(II) Oxide (PbO):
- In this reaction, PbO is reduced to lead (Pb).
- The oxidation state of lead decreases from +2 in PbO to 0 in elemental Pb.
2. Carbon (C):
- Carbon is oxidised to carbon dioxide (CO2).
- The oxidation state of carbon increases from 0 in elemental C to +4 in CO2.
Identifying the Substance Being Oxidised
- In this specific reaction, carbon (C) is the substance that undergoes oxidation.
- It loses electrons and its oxidation state increases, making carbon the reducing agent.
Conclusion
- Therefore, the correct answer is option 'B' (C), as it is the substance that is oxidised in this reaction.
By understanding the changes in oxidation states, we can clearly see that carbon is the oxidised component, while lead oxide is reduced.
Which form of energy is responsible for the decomposition reactions ?- a)Heat
- b)All of these
- c)Electricity
- d)light
Correct answer is option 'B'. Can you explain this answer?
Which form of energy is responsible for the decomposition reactions ?
a)
Heat
b)
All of these
c)
Electricity
d)
light
| | Sahana Menon answered |
Decomposition reactions and energy:
There are various forms of energy that can drive decomposition reactions, breaking down compounds into simpler substances.
All of these:
- Heat: Many decomposition reactions are initiated by heating the compound, which provides the necessary energy to break bonds and start the decomposition process. This is a common method used in industries and laboratories.
- Electricity: In some cases, passing an electric current through a compound can trigger decomposition reactions. This is known as electrolysis and is commonly used in processes like electroplating and water electrolysis.
- Light: Certain compounds can undergo decomposition reactions when exposed to light, especially ultraviolet light. This phenomenon is known as photolysis and is utilized in various chemical reactions.
Therefore, all of these forms of energy - heat, electricity, and light - can be responsible for driving decomposition reactions. Each form of energy provides the necessary activation energy to break the existing bonds in a compound, leading to its decomposition into simpler substances.
There are various forms of energy that can drive decomposition reactions, breaking down compounds into simpler substances.
All of these:
- Heat: Many decomposition reactions are initiated by heating the compound, which provides the necessary energy to break bonds and start the decomposition process. This is a common method used in industries and laboratories.
- Electricity: In some cases, passing an electric current through a compound can trigger decomposition reactions. This is known as electrolysis and is commonly used in processes like electroplating and water electrolysis.
- Light: Certain compounds can undergo decomposition reactions when exposed to light, especially ultraviolet light. This phenomenon is known as photolysis and is utilized in various chemical reactions.
Therefore, all of these forms of energy - heat, electricity, and light - can be responsible for driving decomposition reactions. Each form of energy provides the necessary activation energy to break the existing bonds in a compound, leading to its decomposition into simpler substances.
When a black and white photographic film is exposed to light, the grey colour on the photographic film is due to presence of- a)Ag2O
- b)Ag
- c)Br2
- d)All of these
Correct answer is option 'B'. Can you explain this answer?
When a black and white photographic film is exposed to light, the grey colour on the photographic film is due to presence of
a)
Ag2O
b)
Ag
c)
Br2
d)
All of these
| | Ritu Saxena answered |
A strip or sheet of transparent plastic film base is coated with gelatin emulsion containing small light sensitive silver halide crystals on one side. When the exposed silver halide grains are developed, they are converted to metallic silver which appears as the black part of the film due to blocking of light.
Therefore, the image on an exposed and developed photographic film is due to Ag.
Therefore, the image on an exposed and developed photographic film is due to Ag.
Assertion (A): The iron nail becomes brownish in color and the blue color of copper sulfate solution fades.Reason (R): In the reaction Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s), iron displaces copper in the copper sulfate solution.- a)If both Assertion and Reason are true and Reason is the correct explanation of Assertion
- b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- c)If Assertion is true but Reason is false
- d)If both Assertion and Reason are false
Correct answer is option 'A'. Can you explain this answer?
Assertion (A): The iron nail becomes brownish in color and the blue color of copper sulfate solution fades.
Reason (R): In the reaction Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s), iron displaces copper in the copper sulfate solution.
a)
If both Assertion and Reason are true and Reason is the correct explanation of Assertion
b)
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
c)
If Assertion is true but Reason is false
d)
If both Assertion and Reason are false
| | Lakesway Classes answered |
- The Assertion is true as the iron nail indeed becomes brownish and the blue color of the copper sulfate solution fades due to the displacement reaction described.
- The Reason is also true as iron displaces copper from the copper sulfate solution.
- The Reason is the correct explanation of the Assertion because the observed color changes are a direct result of the displacement reaction where iron replaces copper in the solution.
Which of the following gases can be used for storage of fresh sample of an oil for a long time?- a)Carbon dioxide or oxygen
- b)Carbon dioxide or helium
- c)Nitrogen or oxygen
- d)Nitrogen or helium
Correct answer is option 'D'. Can you explain this answer?
Which of the following gases can be used for storage of fresh sample of an oil for a long time?
a)
Carbon dioxide or oxygen
b)
Carbon dioxide or helium
c)
Nitrogen or oxygen
d)
Nitrogen or helium
| | Vidhi dubey answered |
Answer:
Introduction:
When storing a fresh sample of oil for a long time, it is important to prevent its degradation or oxidation. This can be achieved by using an appropriate gas to create an inert atmosphere that minimizes contact with oxygen, moisture, and other reactive substances. Among the options given, nitrogen or helium are the most suitable gases for this purpose.
Explanation:
Nitrogen:
- Nitrogen is an inert gas, meaning it is chemically unreactive and does not readily react with other substances.
- It is abundantly available in the atmosphere and is commonly used for various industrial and laboratory applications.
- When used for storing oil samples, nitrogen replaces the oxygen in the storage container, thus creating an oxygen-free environment.
- This prevents oxidation and slows down the degradation of the oil, helping to maintain its freshness and quality over a long period of time.
Helium:
- Helium is another inert gas that is chemically stable and does not react with other substances.
- It is lighter than air and has low solubility in most liquids, including oil.
- When used as a storage gas, helium creates a protective blanket over the oil sample, preventing oxygen and moisture from coming into contact with the oil.
- This helps to maintain the oil's freshness and prevents degradation or oxidation.
Comparison:
Both nitrogen and helium are suitable for storing oil samples for a long time. However, there are a few key differences between the two gases:
- Availability: Nitrogen is more readily available and less expensive compared to helium, which is relatively rare and more expensive.
- Density: Helium is lighter than air and has low solubility in oil, making it more effective in creating a protective blanket over the oil sample.
- Cost: Nitrogen is generally more cost-effective and practical for most applications. Helium is typically reserved for specialized or high-value samples due to its higher cost.
Conclusion:
In conclusion, nitrogen or helium can be used for the storage of fresh samples of oil for a long time. Both gases create an inert atmosphere that prevents oxidation and degradation of the oil. Nitrogen is more commonly used due to its availability and cost-effectiveness, while helium is preferred for specialized or high-value samples.
Introduction:
When storing a fresh sample of oil for a long time, it is important to prevent its degradation or oxidation. This can be achieved by using an appropriate gas to create an inert atmosphere that minimizes contact with oxygen, moisture, and other reactive substances. Among the options given, nitrogen or helium are the most suitable gases for this purpose.
Explanation:
Nitrogen:
- Nitrogen is an inert gas, meaning it is chemically unreactive and does not readily react with other substances.
- It is abundantly available in the atmosphere and is commonly used for various industrial and laboratory applications.
- When used for storing oil samples, nitrogen replaces the oxygen in the storage container, thus creating an oxygen-free environment.
- This prevents oxidation and slows down the degradation of the oil, helping to maintain its freshness and quality over a long period of time.
Helium:
- Helium is another inert gas that is chemically stable and does not react with other substances.
- It is lighter than air and has low solubility in most liquids, including oil.
- When used as a storage gas, helium creates a protective blanket over the oil sample, preventing oxygen and moisture from coming into contact with the oil.
- This helps to maintain the oil's freshness and prevents degradation or oxidation.
Comparison:
Both nitrogen and helium are suitable for storing oil samples for a long time. However, there are a few key differences between the two gases:
- Availability: Nitrogen is more readily available and less expensive compared to helium, which is relatively rare and more expensive.
- Density: Helium is lighter than air and has low solubility in oil, making it more effective in creating a protective blanket over the oil sample.
- Cost: Nitrogen is generally more cost-effective and practical for most applications. Helium is typically reserved for specialized or high-value samples due to its higher cost.
Conclusion:
In conclusion, nitrogen or helium can be used for the storage of fresh samples of oil for a long time. Both gases create an inert atmosphere that prevents oxidation and degradation of the oil. Nitrogen is more commonly used due to its availability and cost-effectiveness, while helium is preferred for specialized or high-value samples.
Electrolysis of water is decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is- a)1 : 1
- b)2 : 1
- c)4 : 1
- d)1 : 2
Correct answer is option 'B'. Can you explain this answer?
Electrolysis of water is decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is
a)
1 : 1
b)
2 : 1
c)
4 : 1
d)
1 : 2
| | Tanvi choudhary answered |
Understanding Electrolysis of Water
Electrolysis of water involves splitting water (H2O) into its constituent gases, hydrogen and oxygen, using an electric current. This process can be represented by the chemical equation:
2 H2O(l) → 2 H2(g) + O2(g)
Mole Ratio of Gases
In the reaction:
- 2 moles of water produce:
- 2 moles of hydrogen gas (H2)
- 1 mole of oxygen gas (O2)
From this equation, we can derive the mole ratio of hydrogen to oxygen.
Mole Ratio Calculation
- Hydrogen (H2) produced: 2 moles
- Oxygen (O2) produced: 1 mole
Thus, the mole ratio of hydrogen to oxygen is:
- 2 moles H2 : 1 mole O2
This simplifies to:
- 2 : 1
Conclusion
Therefore, during the electrolysis of water, the correct mole ratio of hydrogen to oxygen gases liberated is indeed 2 : 1. This means for every 2 moles of hydrogen produced, 1 mole of oxygen is released, confirming that option 'B' is correct.
Understanding this ratio is crucial in various applications, including fuel cell technology and industrial processes involving hydrogen production.
Electrolysis of water involves splitting water (H2O) into its constituent gases, hydrogen and oxygen, using an electric current. This process can be represented by the chemical equation:
2 H2O(l) → 2 H2(g) + O2(g)
Mole Ratio of Gases
In the reaction:
- 2 moles of water produce:
- 2 moles of hydrogen gas (H2)
- 1 mole of oxygen gas (O2)
From this equation, we can derive the mole ratio of hydrogen to oxygen.
Mole Ratio Calculation
- Hydrogen (H2) produced: 2 moles
- Oxygen (O2) produced: 1 mole
Thus, the mole ratio of hydrogen to oxygen is:
- 2 moles H2 : 1 mole O2
This simplifies to:
- 2 : 1
Conclusion
Therefore, during the electrolysis of water, the correct mole ratio of hydrogen to oxygen gases liberated is indeed 2 : 1. This means for every 2 moles of hydrogen produced, 1 mole of oxygen is released, confirming that option 'B' is correct.
Understanding this ratio is crucial in various applications, including fuel cell technology and industrial processes involving hydrogen production.
Assertion (A): Burning of natural gas is an example of an exothermic reaction.Reason (R): Exothermic reactions release heat energy along with the formation of products.- a)If Assertion is true but Reason is false
- b)If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- c)If both Assertion and Reason are true and Reason is the correct explanation of Assertion
- d)If both Assertion and Reason are false
Correct answer is option 'C'. Can you explain this answer?
Assertion (A): Burning of natural gas is an example of an exothermic reaction.
Reason (R): Exothermic reactions release heat energy along with the formation of products.
a)
If Assertion is true but Reason is false
b)
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
c)
If both Assertion and Reason are true and Reason is the correct explanation of Assertion
d)
If both Assertion and Reason are false
 | Kamna Science Academy answered |
Let's analyze the statements:
Assertion (A): Burning of natural gas is an example of an exothermic reaction.
- This is true because burning natural gas (methane, CH4) releases heat energy.
Reason (R): Exothermic reactions release heat energy along with the formation of products.
- This is also true because exothermic reactions are characterized by the release of heat energy during the reaction process.
Since both statements are true and the Reason correctly explains the Assertion: If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
The process of coating iron with zinc is called- a)Electroplating
- b)Reduction
- c)Polishing
- d)Galvanisation
Correct answer is option 'D'. Can you explain this answer?
The process of coating iron with zinc is called
a)
Electroplating
b)
Reduction
c)
Polishing
d)
Galvanisation
| | Ritu Saxena answered |
Galvanisation is the process of coating iron with zinc in order to prevent its rusting.
Identify the substances that are oxidised and the substances that are reduced in the following reaction.Fe2O3 + 2Al → Al2O3 + 2Fe- a)Fe2O3
- b)Al
- c)Fe
- d)Both A and B
Correct answer is option 'D'. Can you explain this answer?
Identify the substances that are oxidised and the substances that are reduced in the following reaction.
Fe2O3 + 2Al → Al2O3 + 2Fe
a)
Fe2O3
b)
Al
c)
Fe
d)
Both A and B
 | Kds Coaching answered |
To identify the substances that are oxidized and reduced in the given reaction:
Reaction: Fe2O3 + 2Al → Al2O3 + 2Fe
- Oxidation involves the loss of electrons.
- Reduction involves the gain of electrons.
- Iron (Fe) in Fe₂O₃:
- In Fe₂O₃, iron is in the +3 oxidation state.
- In elemental Fe, the oxidation state is 0.
- Thus, Fe is reduced from +3 to 0.
- Aluminum (Al):
- In elemental Al, the oxidation state is 0.
- In Al₂O₃, aluminum is in the +3 oxidation state.
- Thus, Al is oxidized from 0 to +3.
Substances:
- Substance reduced: Fe₂O₃ (iron is reduced to Fe).
- Substance oxidized: Al (aluminum is oxidized to Al₂O₃).
Correct Answer: (d) Both A and B
Explanation: Fe₂O₃ is reduced, and Al is oxidized.
Explanation: Fe₂O₃ is reduced, and Al is oxidized.
What is the substance gaining oxygen and being oxidized during the described reaction?
- a)Cu
- b)O
- c)CuO
- d)Not a redox reaction
Correct answer is option 'A'. Can you explain this answer?
What is the substance gaining oxygen and being oxidized during the described reaction?
a)
Cu
b)
O
c)
CuO
d)
Not a redox reaction
| | Nk Classes answered |
- In a redox reaction, one substance is oxidized (loses electrons) and another is reduced (gains electrons).
- Oxidation involves the gain of oxygen.
- Copper (Cu) gains oxygen to form CuO, thus it is oxidized.
- Therefore, the substance gaining oxygen and being oxidized is copper (Cu).
- Correct answer: A: Cu
- Oxidation involves the gain of oxygen.
- Copper (Cu) gains oxygen to form CuO, thus it is oxidized.
- Therefore, the substance gaining oxygen and being oxidized is copper (Cu).
- Correct answer: A: Cu
In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature?- a)2 H2 (g) + O2 (l) → 2 H2O (l)
- b)2 H2 (l) + O2 (l) → 2 H2O (g)
- c)2 H2 (g) + O2 (g) → 2 H2O (l)
- d)2 H2 (g) + O2 (g) → 2 H2O (g)
Correct answer is option 'C'. Can you explain this answer?
In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature?
a)
2 H2 (g) + O2 (l) → 2 H2O (l)
b)
2 H2 (l) + O2 (l) → 2 H2O (g)
c)
2 H2 (g) + O2 (g) → 2 H2O (l)
d)
2 H2 (g) + O2 (g) → 2 H2O (g)
| | Ankit reddy answered |
Explanation:
Correct Option:
C. 2 H2 (g) + O2 (g) → 2 H2O (g)
Explanation:
- State Symbols: The state symbols used in chemical equations represent the physical state of the reactants and products involved in the reaction. The most common state symbols are (s) for solid, (l) for liquid, (g) for gas, and (aq) for aqueous solutions.
- Given Equation: 2 H2 (g) + O2 (g) → 2 H2O (g)
- Interpretation: In the given chemical equation, the reactants hydrogen gas (H2) and oxygen gas (O2) are both in the gaseous state, which is represented by (g). The products formed, water (H2O), is also in the gaseous state, as indicated by the (g) state symbol.
- Explanation of Correctness: At reaction temperature, hydrogen and oxygen exist as gases, and when they react to form water, the resulting water vapor is also in the gaseous state. Therefore, option C is the correct representation of the chemical equation with the appropriate state symbols for the reactants and products involved.
In summary, the correct option is C, where all reactants and products are correctly represented in the gaseous state.
Fe2 O3 + 2 Al → Al2O3 + 2 Fe
The above reaction is an example of a- a)Combination reaction
- b)Double displacement reaction
- c)Displacement reaction
- d)Decomposition reaction
Correct answer is option 'C'. Can you explain this answer?
Fe2 O3 + 2 Al → Al2O3 + 2 Fe
The above reaction is an example of a
The above reaction is an example of a
a)
Combination reaction
b)
Double displacement reaction
c)
Displacement reaction
d)
Decomposition reaction
| | Rohit Sharma answered |
It is an example of displacement reaction. Aluminium being more reactive than iron displaces iron and results in the formation of aluminium oxide.
Which of the following statements about the given reaction are correct ?
3 Fe(s) + 4 H2 O(g) → Fe3O4 (s) + 4 H2(g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as oxidising agent.- a)(i), (ii) and (iii)
- b)(iii) and (iv)
- c)(i), (ii) and (iv)
- d)(ii) and (iv)
Correct answer is option 'C'. Can you explain this answer?
Which of the following statements about the given reaction are correct ?
3 Fe(s) + 4 H2 O(g) → Fe3O4 (s) + 4 H2(g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as oxidising agent.
3 Fe(s) + 4 H2 O(g) → Fe3O4 (s) + 4 H2(g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as oxidising agent.
a)
(i), (ii) and (iii)
b)
(iii) and (iv)
c)
(i), (ii) and (iv)
d)
(ii) and (iv)
| | Vivek Bansal answered |
Here, oxygen combines with water to get oxidized. Oxygen is removed from water hence, it is getting reduced. Water is providing oxygen and it acts as an oxidizing agent.
- On introducing two molecules to each other, one molecule loses an electron. This reaction is called oxidation.
- On introducing two molecules to each other, one molecule gains an electron. This reaction is called reduction.
- The oxidized substance is called a reduction agent. The reduced substance is called an oxidizing agent.
Identify the substance oxidised and the substance reduced in the following reactions.MnO2 + 4HCl —–> MnCl2 + 2H20 + Cl2- a)MnO2 is getting reduced and H20 is getting oxidised.
- b)MnO2 is getting reduced and HCl is getting oxidised.
- c)MnCl2 is getting reduced and HCl is getting oxidised.
- d)HCl is getting reduced and Cl2 is getting oxidised.
Correct answer is option 'B'. Can you explain this answer?
Identify the substance oxidised and the substance reduced in the following reactions.
MnO2 + 4HCl —–> MnCl2 + 2H20 + Cl2
a)
MnO2 is getting reduced and H20 is getting oxidised.
b)
MnO2 is getting reduced and HCl is getting oxidised.
c)
MnCl2 is getting reduced and HCl is getting oxidised.
d)
HCl is getting reduced and Cl2 is getting oxidised.
 | EduRev Class 10 answered |
MnO2 is getting reduced and HCl is getting oxidised.
Which of the following is (are) on endothermic process(es)?
(i) Dilution of sulphuric acid
(ii) Sublimation of dry ice
(iii) Condensation of water vapours
(iv) Evaporation of water- a)(i) and (ii)
- b)(ii) and (iv)
- c)(ii) only
- d)(iii) only
Correct answer is option 'B'. Can you explain this answer?
Which of the following is (are) on endothermic process(es)?
(i) Dilution of sulphuric acid
(ii) Sublimation of dry ice
(iii) Condensation of water vapours
(iv) Evaporation of water
(i) Dilution of sulphuric acid
(ii) Sublimation of dry ice
(iii) Condensation of water vapours
(iv) Evaporation of water
a)
(i) and (ii)
b)
(ii) and (iv)
c)
(ii) only
d)
(iii) only
 | Khusboo jain answered |
Endothermic Processes
Dilution of sulphuric acid
- Dilution of sulphuric acid is an exothermic process as it releases heat during the reaction.
Sublimation of dry ice
- Sublimation of dry ice is an endothermic process as it requires heat input to change the solid directly into a gas without passing through the liquid phase.
Condensation of water vapours
- Condensation of water vapours is an exothermic process as it releases heat when water vapours change into liquid water.
Evaporation of water
- Evaporation of water is an endothermic process as it requires heat input to change liquid water into water vapour.
Therefore, the endothermic processes in the given options are (ii) Sublimation of dry ice and (iv) Evaporation of water. So, the correct answer is option B - (ii) and (iv).
Dilution of sulphuric acid
- Dilution of sulphuric acid is an exothermic process as it releases heat during the reaction.
Sublimation of dry ice
- Sublimation of dry ice is an endothermic process as it requires heat input to change the solid directly into a gas without passing through the liquid phase.
Condensation of water vapours
- Condensation of water vapours is an exothermic process as it releases heat when water vapours change into liquid water.
Evaporation of water
- Evaporation of water is an endothermic process as it requires heat input to change liquid water into water vapour.
Therefore, the endothermic processes in the given options are (ii) Sublimation of dry ice and (iv) Evaporation of water. So, the correct answer is option B - (ii) and (iv).
What is a reduction reaction?- a)addition of hydrogen to a substance
- b)addition of oxygen to a substance
- c)removal of hydrogen from a substance
- d)none of the above
Correct answer is option 'A'. Can you explain this answer?
What is a reduction reaction?
a)
addition of hydrogen to a substance
b)
addition of oxygen to a substance
c)
removal of hydrogen from a substance
d)
none of the above
| | Kds Coaching answered |
In terms of hydrogen and oxygen:
Addition of hydrogen to a substance: Reduction
Removal of oxygen from a substance: Reduction
Therefore, option A, "addition of hydrogen to a substance," correctly defines a reduction reaction.
Which among the following is called double displacement reaction (s)?
(i) Pb + CuCl2 → PbCl2 + Cu
(ii) Na2 SO4 + BaCl2 → BaSO4 + 2 NaCl
(iii) C + O2 → CO2
(iv) CH4 + 2 O2 → CO2 + 2H2O- a)(i) and (iv)
- b)(ii) and (i)
- c)(ii) only
- d)(iii) and (iv)
Correct answer is option 'C'. Can you explain this answer?
Which among the following is called double displacement reaction (s)?
(i) Pb + CuCl2 → PbCl2 + Cu
(ii) Na2 SO4 + BaCl2 → BaSO4 + 2 NaCl
(iii) C + O2 → CO2
(iv) CH4 + 2 O2 → CO2 + 2H2O
(i) Pb + CuCl2 → PbCl2 + Cu
(ii) Na2 SO4 + BaCl2 → BaSO4 + 2 NaCl
(iii) C + O2 → CO2
(iv) CH4 + 2 O2 → CO2 + 2H2O
a)
(i) and (iv)
b)
(ii) and (i)
c)
(ii) only
d)
(iii) and (iv)
| | Radha Iyer answered |
The reactions in which two compounds react by an exchange of ions to form two new compounds are called double displacement reactions. In double replacement reactions, the positive ions exchange negative ion partners. A double replacement reaction is represented by the general equation.
AB + CD → AD + CB
In a double displacement reaction, atoms from two different compounds switch places. The reactants are two compounds and the products are two different compounds.
Na2SO4 + BaCl2 → BaSO4 + 2NaCl
AB + CD → AD + CB
In a double displacement reaction, atoms from two different compounds switch places. The reactants are two compounds and the products are two different compounds.
Na2SO4 + BaCl2 → BaSO4 + 2NaCl
Which of the following substance is reduced in the given reaction below?
PbS(s) + 4H2O2 (aq) → PbSO4(s) + 4H2O- a)Lead sulphide
- b)Hydrogen peroxide
- c)Both lead sulphide and Hydrogen peroxide
- d)Water
Correct answer is option 'B'. Can you explain this answer?
Which of the following substance is reduced in the given reaction below?
PbS(s) + 4H2O2 (aq) → PbSO4(s) + 4H2O
PbS(s) + 4H2O2 (aq) → PbSO4(s) + 4H2O
a)
Lead sulphide
b)
Hydrogen peroxide
c)
Both lead sulphide and Hydrogen peroxide
d)
Water
| | Rahul agarwal answered |
Understanding the Reaction
In the reaction:
PbS(s) + 4H2O2(aq) → PbSO4(s) + 4H2O,
we need to identify which substance is reduced.
Reduction Process
- Definition of Reduction: Reduction is a chemical reaction that involves the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.
Analyzing Hydrogen Peroxide
- Hydrogen Peroxide (H2O2): In this reaction, H2O2 acts as an oxidizing agent. It is known to undergo reduction during the reaction.
- Oxidation State Change: The oxidation state of oxygen in H2O2 is -1, and in water (H2O), it is -2. This change indicates that H2O2 is gaining electrons and being reduced.
Analyzing Lead Sulfide
- Lead Sulfide (PbS): In this reaction, PbS is converted to PbSO4.
- Oxidation State Change: Lead (Pb) in PbS has an oxidation state of +2 in PbSO4, but the lead does not gain electrons. Instead, it is oxidized.
Conclusion
- Final Identification: Since H2O2 is reduced (gaining electrons) and PbS is oxidized (losing electrons), the correct answer is indeed b) Hydrogen peroxide.
Thus, understanding the changes in oxidation states helps clarify the reduction process in this reaction.
In the reaction:
PbS(s) + 4H2O2(aq) → PbSO4(s) + 4H2O,
we need to identify which substance is reduced.
Reduction Process
- Definition of Reduction: Reduction is a chemical reaction that involves the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.
Analyzing Hydrogen Peroxide
- Hydrogen Peroxide (H2O2): In this reaction, H2O2 acts as an oxidizing agent. It is known to undergo reduction during the reaction.
- Oxidation State Change: The oxidation state of oxygen in H2O2 is -1, and in water (H2O), it is -2. This change indicates that H2O2 is gaining electrons and being reduced.
Analyzing Lead Sulfide
- Lead Sulfide (PbS): In this reaction, PbS is converted to PbSO4.
- Oxidation State Change: Lead (Pb) in PbS has an oxidation state of +2 in PbSO4, but the lead does not gain electrons. Instead, it is oxidized.
Conclusion
- Final Identification: Since H2O2 is reduced (gaining electrons) and PbS is oxidized (losing electrons), the correct answer is indeed b) Hydrogen peroxide.
Thus, understanding the changes in oxidation states helps clarify the reduction process in this reaction.
Which of the following are exothermic processes?
(i) Reaction of water with quick lime
(ii) Dilution of an acid
(iii) Evaporation of water
(iv) Sublimation of camphor (crystals)- a)(i) and (ii)
- b)(ii) and (iii)
- c)(i) and (iv)
- d)(iii) and (iv)
Correct answer is option 'A'. Can you explain this answer?
Which of the following are exothermic processes?
(i) Reaction of water with quick lime
(ii) Dilution of an acid
(iii) Evaporation of water
(iv) Sublimation of camphor (crystals)
(i) Reaction of water with quick lime
(ii) Dilution of an acid
(iii) Evaporation of water
(iv) Sublimation of camphor (crystals)
a)
(i) and (ii)
b)
(ii) and (iii)
c)
(i) and (iv)
d)
(iii) and (iv)
| | Priyanka Kapoor answered |
Exothermic reactions are chemical reactions that release energy as heat or light.
- A large amount of heat is released when quick lime reacts with water, along with the formation of calcium hydroxide.
- Similarly, the process of dissolving an acid or base in water is a highly exothermic reaction. Water should never be added to acid, but the acid can be added to water for dilution.
- Evaporation of water and sublimation of camphor are endothermic reactions.
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