Question

Calculate the mass of $6.02\times {10}^{21}$ molecules of nitrogen.

Answer 1

1 mole of $N_2$ contain $6.02\times {10}^{23}$ molecules

No. of moles of $N_2=\frac{6.02\times {10}^{21}}{6.02\times {10}^{23}}=0.01$moles

Molar mass of $N_2$ $=14\times 2=28g/mol$

Mass of $N_2=(0.01\times 28)g=0.280g$