Question

Rearrange the following (I to IV) in the order of in creasing masses and choose the correct answer from (a), (b), (c), (d). (atomic masses: $N =14,\, O =16,\, Cu =63$)
I. $1$ molecule of oxygen
II. $1$ atom of nitrogen
III. $1 \times 10^{10} g$ molecular weight of oxygen
IV. $1 \times 10^{-18} g$ atomic weight of copper

• A. II < I < IV < III
• B. IV < III < II < I
• C. II < III < I < IV
• D. III < IV < I < II

Answer 1

Answer: (A)

(i) 1 Molecule of $O _{2}=\frac{32}{6.023 \times 10^{23}}$
$=0.5 \times 10^{-23} gm$
(ii) 1 atom of $N =\frac{14}{6.023 \times 10^{23}}$
$=2.3 \times 10^{-23} gm$
(iii) $10^{-10} gm\, mol$ wt. of oxygen
$=10^{-10} \times 32=3.2 \times 10^{-9} gm$
(iv) $10^{-10} gm$ atom of copper
$=10^{-10} \times 63=6.3 \times 10^{-9} gm$