Consider the given two statements:
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.
Select the correct option:
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×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×2
Hence, both assertion and reason are true and the reason is the correct explanation of assertion.