Solve this question

So, mass of N_A atoms = $\frac{16}{N_A}$ ×N_A = 16 grams

For X₂ type of gas, the mass will be 2×16 = 32 grams

Now, using idela gas equation,
PV =nRT 
$\frac{2x350}{1000}$ =n ×0.08 ×273   
(1000 is in denomination to convert volume into litre.)
on solving, n = 0.032051
now, 
Mass of one mole of X₂ gas             = 32 gram

Mass of 0.032051 moles of X₂ gas = 32 ×0.032051
                                                                =1.02 g ~ 1 gram

Option A is correct.