Question

The lightest as is:

• A. $N_2$
• B. $Ar$
• C. $Rn$
• D. $He$

Answer 1

Answer: (D)

$He$

Answer 2

The lightest gas is hydrogen (H). Its atomic weight is $1.008$. But among the mentioned gases lightest one is helium (He). Its atomic weight is $4.003$.