First, find the number of moles for each element. The molar mass for nitrogen is 14 g/mol and that of hydrogen is 1 g/mol.
1.40 g N / 14 g/mol = 0.1 mol N
0.20 g H / 1 g/mol = 0.2 mol H
Find the mole ratio. Divide both numbers with the much lower value. In this case, it is 0.1 mol N.
For N: 0.1 ÷ 0.1 = 1
For H: 0.2÷0.1 = 2
Thus, the empirical formula is [tex] NH_{2} [/tex].