Test: Chemical Reactions & Equations - 3


25 Questions MCQ Test NCERT Textbooks (Class 6 to Class 12) | Test: Chemical Reactions & Equations - 3


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QUESTION: 1

Which of the following is a combination reaction?

Solution:

Balanced Equation:
H2 + 2Cl2 = 2HCl2

The above reaction is an example of combination reaction because two different elements are combining to form a single compound.

QUESTION: 2

Which of the following represent a double displacement reaction?

Solution:

It is a double displacement reaction. Na will displace Ag and combine with NO3 to form NaNO3. Ag will then combine with Cl and form AgCl. So the products of the reaction are AgCl and NaNO3.

QUESTION: 3

Which of the following is a displacement reaction?

Solution:

Fe + CuSo4 = FeSO4 + Cu 
is displacement reaction.
In these reaction iron (Fe) displace copper (Cu) 
Hence, it is a displacement type of reaction.

QUESTION: 4

The reaction H2 + Cl2 → 2HCl is a –

Solution:

Balanced equation:
H2 + 2Cl2 = 2HCl2

The above reaction is an example of combination reaction. 

QUESTION: 5

Which of the following is a decomposition reaction?

Solution:

A common decomposition of a chlorate is in the reaction of potassium chlorate where oxygen is the product. This can be written as:

2KClO→ 2KCl + 3O2

QUESTION: 6

Which of the following statement is incorrect?

Solution:

Oxidizing agent, or oxidantgains electrons and is reduced in a chemical reaction. Also known as the electron acceptor, the oxidizing agent is normally in one of its higher possible oxidation states because it will gain electrons and be reduced. Examples of oxidizing agents include halogens, potassium nitrate, and nitric acid. 

QUESTION: 7

Which of the following is a combustion reaction –

Solution:

Oxidation reaction which produce heat and light is called combustion. Here, when we burn petrol in the presence of Oxygen, it produces heat and light which proves that it is a combination reaction.

So option C is the correct answer. 

QUESTION: 8

A chemical equation is said to be balanced if number of

Solution:

Balanced chemical equation: A balanced equation is a chemical equation in which number of atoms of each element is equal on both sides of the equation i.e number ofatoms of an element on reactant side = number of atoms of that element on the product side.

QUESTION: 9

Which statement is correct about the following reaction?
ZnO + CO → Zn + CO2

Solution:

ZnO(s)+CO(s)→Zn(s)+CO2(g)

Since oxygen has combined with carbon, carbon is the one that is oxidized and ZnO is the oxidizing agent. Similarly carbon has taken the oxygen of ZnO, carbon is the reducing agent and ZnO is the one that has been reduced.
Reducing agent-C
Oxidizing agent-ZnO
Oxidized-CO
Reduced- ZnO

QUESTION: 10

The reaction C + O2  → CO2 + Heat is a

Solution:

C + O2  → CO2 + Heat

This is a Combination reaction because the reaction which takes place between a metal and a non-metal. Ionic compounds are formed when most metals react with the non-metals.

This is also Oxidation reaction because carbon got oxidized.

This is also Exothermic reaction because a chemical reaction in which heat energy is produced.

QUESTION: 11

Conversion of CaCO3 in to CaO as per following reaction is an example of –
CaCO3 → CaO + CO2

Solution:

In the given reaction,

the compound breaks down into two simpler products.

QUESTION: 12

Fe2O3 + 2Al → Al2O3 + 2Fe  This reaction is an example of –

Solution:

Fe2O3 + 2Al → Al2O3 + 2Fe
This reaction is an example of a d)displacement reaction.
Here Aluminum is more reactive metal than Fe. Therefore Al will displace Fe from its oxide.

QUESTION: 13

In reaction SO2 + 2H2S → 2H2O + 3S, the reducing agent is –

Solution:

In the reaction SO2 is reduced to S as oxygen 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.

QUESTION: 14

An element X on exposure to moist air turns reddish-brown and a new compound Y is formed. The substance X and Y are

Solution:
QUESTION: 15

What happens when dil hydrochloric acid is added to iron fillings?

Solution:

Hydrogen gas and iron chloride are produced.

Fe + HCl --> FeCl2 + H2

QUESTION: 16

When Iron nails are added to an aquous solution of copper sulphate, a chemical change occurs, which of the following is not true about this reaction?

Solution:

When iron nail is dipped in Copper sulphate, it takes reaction between them and Copper sulphate changes its color from blue to light green. 

This should determine more reactive than copper. 

This could replace copper from CuSO4, and blue color and FeSO4 is in light green color. It will change its colors due to copper iron nails functions.

QUESTION: 17

Some crystals of copper sulphate were dissolved in water. The colour of the solution obtained would be

Solution:

Copper sulphate aqueous solution is blue in colour .

QUESTION: 18

The colour of zinc metal is

Solution:

Zinc is a bluish-silver, lustrous metal that tarnishes in moist air, producing a layer of carbonate. It is somewhat brittle at room temperature but malleable above 100oC. It is a fair conductor of electricity, and burns in air with a bright bluish-green flame producing white clouds of the oxide.

QUESTION: 19

Which one of the following will be required to identify the gas evolved when dilute HCl reacts with zinc metal?

Solution:

The gas evolved when zinc reacts with dilute HCl is Hydrogen gas.

Zinc being an active metal readily reacts with hydrochloric acid at room temperature to form soluble zinc chloride and hydrogen.

Zn + 2HCl = ZnCl2 + H2.

As zinc displaces hydrogen from HCl, this a displacement reaction. Hydrogen gas is usually prepared in the laboratory by this reaction.

QUESTION: 20

Can we store CuSO4 in iron container and why?

Solution:

Because iron is more reactive than copper, therefore, reaction will take place and hence, the iron pot will get destroyed.

QUESTION: 21

Which of the following is the incorrect method of preventing rusting?

Solution:
QUESTION: 22

PbI2 is

Solution:

It is a bright yellow odourless crystalline solid, that becomes orange and red when heated. It was formerly called plumbous iodide.

QUESTION: 23

The element or compound which undergoes reduction is

Solution:

An oxidizing agent, or oxidantgains electrons and is reduced in a chemical reaction. Also known as the electron acceptor, the oxidizing agent is normally in one of its higher possible oxidation states because it will gain electrons and be reduced.

QUESTION: 24

Which of the following is not an example of chemical change?

Solution:

The process of changing water vapour into water is called condensation. It is not a chemical reaction

QUESTION: 25

ANa+BH2O→CNaOH+DH2. What would come in place of A , B C and D to balance the equation

Solution:

2 Na + 2H2O gives 2NaOH + H2 

So option B is Correct answer.