Answer:
14 g of N2
Explanation:
If we look at the options, we will notice that the correct answer needs to be a gas that has about half of the molecular mass of the gas.
If we consider nitrogen gas whose molecular mass is 28g/mol, half of the molecular mass is 14 g.
So;
28g of N2 contains 6.02 × 10^23 molecules of N2
14g of N2 contains 14 × 6.02 × 10^23 /28
= 3.0 x 10^23