Which one of the following is the lightest

(a) Moles = given wt./molecular wt.
Weight of H₂ = mole x molecular wt.
                  = 0.2 x 2 = 0.4 g
(b) 6.023 x 10²³ represents 1 mole
Thus 6.023 x 10²² will represent 0.1 mole
Weight of N₂ = 0.1 x 28 = 2.8 g
(c) Weight of silver = 0.1 g
(d) Weight of oxygen = 32 x 0.1 = 3.2 g
Thus, 0.1 g silver is the lightest.