Class 10 Exam  >  Class 10 Notes  >  Science Class 10  >  Lakhmir Singh & Manjit Kaur Solutions: Chemical Reactions & Equations - 2

Lakhmir Singh & Manjit Kaur Solutions: Chemical Reactions & Equations - 2 | Science Class 10 PDF Download

(Page - 20)

Question 22:
(a) Explain, with an example, how the physical states of the reactants and products can be shown in a chemical equation.
(b) Balance the following equation and add state symbols :
Zn + HCl ——– > ZnCl2 + H2
(c) Convey the following information in the form of a balanced chemical equation :
“An aqueous solution of ferrous sulphate reacts with an aqueous solution of sodium hydroxide to form a precipitate of ferrous hydroxide and sodium sulphate remains in solution.”
Solution :

(a) The physical states of the reactants and products are shown by putting the “state symbols”
in an equation.
For example: Zn (s) + H2SO4 (aq) —–> ZnSO4 (aq) + H2(g)Showing physical state of reactants and productsShowing physical state of reactants and productsb) Zn (s) + 2HCl(aq) —–> ZnCl2 (aq) + H2 (g)
(c) FeSO4(aq)+ 2NaOH (aq) —–> Fe(OH)2 (s) + Na2SO4(aq)


Question 23:
Write any two observations in an activity that may suggest that a chemical reaction has taken place. Give an example in support of your answer.
Solution :

  1.  Evolution of gas.
    For example: When sodium carbonate reacts with dilute hydrochloric acid, carbon dioxide gas is evolved.
  2.  Formation of a precipitate.
    For example: When potassium iodide solution is added to a solution of lead nitrate, a yellow precipitate of lead iodide is formed.

Question 24:
(a) Aluminium hydroxide reacts with sulphuric acid to form aluminium sulphate and water. Write a balanced equation for this reaction.
(b) Balance the following chemical equation :
MnO2 + HCl —–> MnCl2 + Cl2 + H2O
Solution :

(a) 2Al(OH)3+ 3H2SO4 —–> Al2(SO4)3+ 6H2O
(b) MnO2+ 4HCl —–> MnCl2+ Cl2 + 2H2O


Question 25:
 Write the balanced equations for the following reactions, and add the state symbols (a)  Magnesium carbonate reacts with hydrochloric acid to produce magnesium chloride, carbon dioxide, and water.
(b) Sodium hydroxide reacts with sulphuric acid to produce sodium sulphate and water.
Solution :

(a) MgCO3 (s) + 2HCl (aq) MgCl2 (aq) + CO(g) + H2O (l)
(b) 2NaOH (aq) + H2SO4 (aq) Na2SO4 (aq) + 2H2O (l)


Question 26:
Carbon monoxide reacts with hydrogen under certain conditions to form methanol (CH3OH). Write a balanced chemical equation for this reaction indicating the physical states of reactants and product as well as the conditions under which this reaction takes place.
Solution :

Lakhmir Singh & Manjit Kaur Solutions: Chemical Reactions & Equations - 2 | Science Class 10
The conditions for this reaction to take place are a pressure of 300 atmospheres (written as 300 atm), a temperature of 300oC, and a catalyst which is a mixture of zinc oxide and chromium oxide (ZnO + CrO3).


Question 27:
(a) Potassium chlorate (KClO3) on heating forms potassium chloride and oxygen. Write a balanced equation
for this reaction and indicate the evolution of gas.
(b) Rewrite the following information in the form of a balanced chemical equation :
Magnesium burns in carbon dioxide to form magnesium oxide and carbon.
Solution :

(a) 2KClO3
(s) 2KCl (s) + 3O2 (g)
(b) 2Mg + CO—–> 2MgO + C


Question 28:
(a) Substitute formulae for names and balance the following equation :
Calcium carbonate reacts with hydrochloric acid to produce calcium chloride, water, and carbon dioxide gas.
(b) Write a balanced chemical equation with state symbols for the following reaction: Sodium hydroxide solution reacts with a hydrochloric acid solution to produce sodium chloride solution and water.
Solution :

(a) CaCO3+ 2HCl —–> CaCl2 + H2O + CO2
(b) NaOH (aq) + HCl(aq) —–> NaCl (aq) + H2O (l)


Question 29:
Ammonia reacts with oxygen to form nitrogen and water. Write a balanced chemical equation for this reaction. Add the state symbols for all the reactants and products.
Solution :

4NH3 (g)+ 3O(g) —–> 2N2 (g) + 6H2O (l)


Question 30:
Write a balanced chemical equation for the process of photosynthesis giving the physical states of all the substances involved and the conditions of the reaction.
Solution :

6CO2 (g) + 6H2OC6 —–> H12O6 (aq) + 6O2(g)
Carbon
dioxide Water
Glucose Oxygen


Question 31:
Translate the following statement into a chemical equation and then balance it :
Barium chloride solution reacts with aluminium sulphate solution to form a precipitate of barium sulphate and aluminium chloride solution.
Solution :

3BaCl2(aq) + Al2(SO4)3 (aq) —–> 3BaSO4 (s) + 2AlCl3(aq)


Question 32:
When potassium nitrate is heated, it decomposes into potassium nitrite and oxygen. Write a balanced equation for this reaction and add the state symbols of the reactants and products.
Solution :

2KNO3 (s) —–> 2KNO2 (s) + O2(g)


Question 33:
(a) What is meant by a chemical reaction? Explain with the help of an example.
(b) Give one example each of a chemical reaction characterized by :

  1. evolution of a gas
  2. change in colour
  3. formation of a precipitate
  4. change in temperature
  5. change in state.

Solution :
(a)Chemical reactions are the processes in which new substances with new properties are formed.
For example: When magnesium ribbon is heated, it burns in air to form a white powder called magnesium oxide.
(b)The chemical reaction between zinc and dilute sulphuric acid.

  1. The chemical reaction between citric acid and purple coloured potassium permanganate solution is characterized by change in colour (from purple to
    colourless).
  2. The chemical reaction between potassium iodide and lead nitrate is characterized by the formation of a yellow precipitate of lead iodide.
  3. The reaction between quick lime and water to form slaked lime is characterized by a change in temperature.

(Page No. - 21)

Question 34:
(a) State the various characteristics of chemical reactions.
(b) State one characteristic each of the chemical reaction which takes place when :

  1. dilute hydrochloric acid is added to sodium carbonate
  2. lemon juice is added gradually to potassium permanganate solution
  3. dilute sulphuric acid is added to barium chloride solution
  4. quicklime is treated with water
  5. wax is burned in the form of a candle

Solution :
(a) The various characteristics of chemical reactions are:

  1. Evolution of a gas
  2. Formation of a precipitate
  3. Change in colour
  4. Change in temperature
  5. Change in state.

(b) Evolution of carbon dioxide gas

  1. Change in colour from purple to colourless
  2. Formation of white precipitate of barium sulphate
  3. Change in temperature
  4. Change in state from solid to liquid and gas.

Question 35:
(a) What do you understand by exothermic and endothermic reactions ?
(b) Give one example of an exothermic reaction and one of an endothermic reaction.
(c) Which of the following are endothermic reactions and which are exothermic reactions ?

  1. Burning of natural gas
  2. Photosynthesis
  3. Electrolysis of water
  4. Respiration
  5. Decomposition of calcium carbonate

Solution :
(a) Those reactions in which heat is evolved are known as exothermic reactions.
The reactions in which heat is absorbed are known as endothermic reactions.
(b) Example of exothermic reaction:
C (s) + O2 (g) —–> CO2 + Heat
Example of endothermic reaction:
N2 (g) + O2 (g) + Heat —–> 2NO (g)
(c) Endothermic reactions: Photosynthesis, Electrolysis of water, Decomposition of calcium carbonate.
Exothermic reactions: Burning of natural gas, Respiration.


(Page No. - 22)

Question 46:
When the solution of substance X is added to a solution of potassium iodide, then a yellow solid separates out from the solution.
(a) What do you think substance X is likely to be ?
(b) Name the substance which the yellow solid consists of.
(c) Which characteristic of chemical reactions is illustrated by this example ?
(d) Write a balanced chemical equation for the reaction which takes place. Mention the physical states of all the reactants and products involved in the chemical equation.
Solution :

(a) Lead nitrate.
(b) Lead iodide.
(c) Formation of a precipitate.
(d) Pb(NO3)2 (aq) + 2KI (aq) —–> PbI2 (s) + 2KNO(aq)

Question 47:
When water is added gradually to a white solid X, a hissing sound is heard and a lot of heat is produced forming a product Y. A suspension of Y in water is applied to the walls of a house during white washing. A clear solution of Y is also used for testing carbon dioxide gas in the laboratory.
(a) What could be solid X ? Write its chemical formula.
(b) What could be product Y ? Write its chemical formula.
(c) What is the common name of the solution of Y which is used for testing carbon dioxide gas ?
(d) Write chemical equation of the reaction which takes place on adding water to solid X.
(e) Which characteristic of chemical reactions is illustrated by this example ?
Solution :

(a) Calcium oxide, CaO.
(b) Calcium hydroxide, Ca(OH)2
(c) Lime water.
(d) CaO + H2O —–> Ca(OH)2
(e) Change in temperature.


Question 48:
When metal X is treated with a dilute acid Y, then a gas Z is evolved which burns readily by making a little explosion.
(a) Name any two metals which can behave like metal X.
(b) Name any two acids which can behave like acid Y.
(c) Name the gas Z.
(d) Is the gas Z lighter than or heavier than air ?
(e)Is the reaction between metal X and dilute acid Y exothermic or endothermic ?
(f) By taking a specific example of metal X and dilute acid Y, write a balanced chemical equation for the reaction which takes place. Also indicate physical states of all the reactants and products.
Solution :

(a) Zinc and Iron.
(b) Dilute hydrochloric acid and dilute sulphuric acid.
(c) Hydrogen.
(d) Lighter than air.
(e) Exothermic.
(f) Suppose metal X is zinc (Zn) and acid Y is dilute hydrochloric acid (HCl) ;
Zn (s) + 2HCl (aq) ZnCl2 (aq) + H2 (g)


Question 49:
A solid substance P which is very hard is used in the construction of many buildings, especially flooring. When substance P is heated strongly, it decomposes to form another solid Q and a gas R is given out. Solid Q reacts with water with the release of a lot of heat to form a substance S. When gas R is passed into a clear solution of substance S, then a white precipitate of substance T is formed. The substance T has the same chemical composition as starting substance P.
(a) What is substance P ? Write its common name as well as chemical formula.
(b) What is substance Q ?
(c) What is gas R ?
(d) What is substance S ? What is its clear solution known as ?
(e) What is substance T ? Name any two natural forms in which substance T occurs in nature.
Solution :
(a) Calcium carbonate (limestone), CaCO3
(b) Calcium oxide, CaO
(c) Carbon dioxide, CO2
(d) Calcium hydroxide, Ca(OH)2; Lime water.
(e) Calcium carbonate; Limestone and Marble.

The document Lakhmir Singh & Manjit Kaur Solutions: Chemical Reactions & Equations - 2 | Science Class 10 is a part of the Class 10 Course Science Class 10.
All you need of Class 10 at this link: Class 10
105 videos|457 docs|112 tests

FAQs on Lakhmir Singh & Manjit Kaur Solutions: Chemical Reactions & Equations - 2 - Science Class 10

1. What is the difference between a chemical reaction and a chemical equation?
Ans. A chemical reaction refers to the process in which one or more substances are transformed into new substances with different properties. On the other hand, a chemical equation is a symbolic representation that shows the reactants and products involved in a chemical reaction, along with their respective stoichiometric coefficients.
2. How can we balance a chemical equation?
Ans. To balance a chemical equation, we need to ensure that the number of atoms of each element is the same on both sides of the equation. This can be achieved by adjusting the coefficients in front of the chemical formulas. The balancing process involves using the principle of conservation of mass.
3. What are the different types of chemical reactions?
Ans. There are several types of chemical reactions, including: 1. Combination reactions: Two or more substances combine to form a single product. 2. Decomposition reactions: A single reactant breaks down into two or more products. 3. Displacement reactions: One element replaces another element in a compound. 4. Double displacement reactions: Positive and negative ions of two compounds exchange places. 5. Redox reactions: Involves the transfer of electrons between reactants, resulting in changes in oxidation states.
4. What are the importance and applications of chemical reactions?
Ans. Chemical reactions are of great importance in various fields, including: 1. Industrial processes: Chemical reactions are used to produce various products on a large scale, such as fertilizers, medicines, plastics, and fuels. 2. Environmental studies: Understanding chemical reactions helps in studying and mitigating environmental issues, such as air pollution and the greenhouse effect. 3. Biological processes: Chemical reactions play a crucial role in biological processes, such as metabolism and digestion. 4. Energy production: Many energy production methods, such as combustion and nuclear reactions, involve chemical reactions. 5. Material science: Chemical reactions are used to synthesize and modify materials with desired properties, such as polymers and alloys.
5. How does a catalyst affect a chemical reaction?
Ans. A catalyst is a substance that speeds up the rate of a chemical reaction without being consumed in the process. It provides an alternative reaction pathway with lower activation energy, allowing the reaction to occur more readily. Catalysts increase the rate of reaction by providing an appropriate surface for reactant molecules to come together and interact. They do not alter the equilibrium position or change the overall energy change of the reaction.
105 videos|457 docs|112 tests
Download as PDF
Explore Courses for Class 10 exam
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev
Download the FREE EduRev App
Track your progress, build streaks, highlight & save important lessons and more!
Related Searches

Free

,

practice quizzes

,

pdf

,

Objective type Questions

,

Semester Notes

,

Sample Paper

,

Important questions

,

shortcuts and tricks

,

MCQs

,

video lectures

,

mock tests for examination

,

Viva Questions

,

study material

,

Summary

,

ppt

,

past year papers

,

Lakhmir Singh & Manjit Kaur Solutions: Chemical Reactions & Equations - 2 | Science Class 10

,

Lakhmir Singh & Manjit Kaur Solutions: Chemical Reactions & Equations - 2 | Science Class 10

,

Extra Questions

,

Lakhmir Singh & Manjit Kaur Solutions: Chemical Reactions & Equations - 2 | Science Class 10

,

Exam

,

Previous Year Questions with Solutions

;