Which of the following has least mass

(a) 2 gm atom of nitrogen = 28 gm
(b) 6 x 10²³ atoms of C has mass = 12 gm
${\text{3 × 10}}^{23} \mathrm{atoms} \mathrm{of} \mathrm{C} \mathrm{has} \mathrm{a} \mathrm{mass} =\frac{12\times 3\times {10}^{23}}{6\times {10}^{23}}=6 \mathrm{gm}$
(c) 1 mole of S has a mass of 32 gm
(d) 7.0 gm of Ag
So, lowest mass = 6 gm of C.