Calculate the gram molecules in 21 g of nitrogen [N = 14]

Gram molecules is the relative molecular mass of a substance expressed in grams.

Relative molecular mass of N₂ = 2 × 14 = 28 g

Gram molecules = Mass (in g)/molecular wt

= 21/28

= 0.75 $\text{gram molecules}$

Hence, gram molecules in 21 g of nitrogen = 0.75 gram molecules