Solutions - CBSE Class 10 Sample Paper for 2022 Boards - Science [MCQ]

Class 10
Solutions to CBSE Sample Paper - Science Class 10

Which of the following correctly represents a balanced chemical equation? 

(A) Fe(s) + 4H 2 O(g) → Fe 3 O 4 (s) + 4H 2 (g) 

(B) 3Fe(s) + 4H 2 O(g) → Fe 3 O 4 (s) + 4H 2 (g) 

(C) 3Fe(s) + H 2 O(g) → Fe 3 O 4 (s) + H 2 (g) 

(D) 3Fe(s) + 4H 2 O(g) → Fe 3 O 4 (s) + H 2 (g)

 

Answer - 

A balanced chemical equation is one in which the number of atoms of both reactants and products are equal. 

 

In reaction A:

 

Fe

H

O

Reactant

1

8

4

Product

3

8

4

 

Since the number of Fe atoms in reactant and product is not equal, it is not a balanced equation.

 

In reaction B:

 

 

Fe

H

O

Reactant

3

8

4

Product

3

8

4

 

Since the number of all atoms in reactants and products is equal, it is a balanced equation.

 

In reaction C:

 

 

Fe

H

O

Reactant

3

2

1

Product

3

2

4

 

Since the number of O atoms in reactant and product is not equal. It is not a balanced equation



In Reaction D:

 

 

Fe

H

O

Reactant

3

8

4

Product

3

2

4

 

Since the number of H atoms is not equal in reactant and product, it is not a balanced equation.


So, the correct answer is (b) - 3Fe(s) + 4H 2 O(g) → Fe 3 O 4 (s) + 4H 2 (g)

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CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. He teaches Science, Economics, Accounting and English at Teachoo