Ncert Exercises & Solutions

Assertion (A):	The empirical mass of ethene is half of its molecular mass.
Reason (R):	The empirical formula represents the simplest whole-number ratio of the various atoms present in a compound.

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:

Molecular formula = Empirical formula \times 2

The empirical formula represents the simplest whole-number ratio of various atoms present in a compound.

The molecular formula of ethene is C₂H₄ . It can be written as (CH₂)₂. Hence, the value of n is 2.

Thus,

Molecular formula = Empirical formula \times 2

Hence, both assertion and reason are true and the reason is the correct explanation of assertion.