Ncert Exercises & Solutions

Assertion (A):	The combustion of 16 g of methane gives 18 g of water.
Reason (R):	In the combustion of methane, water is one of the products.

1.	Both (A) and (R) are true and (R) is the correct explanation of (A).
2.	Both (A) and (R) are true but (R) is not the correct explanation of (A).
3.	(A) is true but (R) is false.
4.	(A) is false but (R) is true.

Hint:

\underset{}{{CH}_{4}} + 2 O_{2} \to {CO}_{2} + \underset{}{2 H_{2} O}

The combustion reaction of methane is as follows:

\underset{1 mol}{{CH}_{4}}

= 16 g + 2 O_{2} \to {CO}_{2} + \underset{2 mol}{2 H_{2} O}

= 36 g

From the equation, it is clear that 1 mole or 16 g CH₄ produces 2 mol or 36 g of H₂O

Thus, the Assertion is false but the reason is true because the amount of water is 36g, not 18g. Water is one of the products.