NIOS Class 10 Science and Technology Chapter4: CHEMICAL REACTION AND EQUATIONS – Chapter-wise Important Questions and Answers

NIOS Class 10 Science and Technology Chapter 4: CHEMICAL REACTION AND EQUATIONS | MCQs, Short & Long Answer Questions | 4: CHEMICAL REACTION AND EQUATIONS

Chapter4: CHEMICAL REACTION AND EQUATIONS

INTEXT QUESTION 4.1

1. Write a chemical equation for each of the following reactions:

(i) Zinc metal reacts with aqueous hydrochloric acid to produce a solution of zinc chloride and hydrogen gas.

(ii) When solid mercury(II) oxide is heated, liquid mercury and oxygen gas are produced.

Answer: The balanced chemical equations are:

(i) Zinc metal reacts with aqueous hydrochloric acid:

Zns+2HClaq→ZnCl2(aq)+H2g

 (ii) On heating mercury(II) oxide:

2HgOs     heat           2Hg(l)+O2(g)

 

2. Balance the following chemical equations:

(i)  H2SO4(aq) + NaOH (aq)→Na2SO4 (aq) + H2O (l)

(ii)  Al s+ HCl aq→ AlCl3 (aq) +H2 (g)

Answer: The Balance chemical equations are :

(i)  H2SO4(aq) + 2NaOH (aq)→Na2SO4 (aq) +2H2O (l)

(ii)  2Al s+ 6HCl aq→ 2AlCl3 (aq) +3H2 (g)

 

3. What is a balanced chemical equation? Why should a chemical equation be balanced?

Answer: A balanced chemical equation is a chemical equation in which the number of atoms of each type involved in the chemical reaction is equal on the reactants and products sides of the equation.

A chemical equation should be balanced because of the law of conservation of mass, which states that mass can neither be created nor destroyed in a chemical reaction. Therefore, the total number of atoms of each element must remain the same before and after the reaction.

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