# Rearrange the following (I to IV) in the order of increasing masses and choose the correct answer from (A), (B), (C) and (D)

Q: Rearrange the following (I to IV) in the order of increasing masses and choose the correct answer from (A), (B), (C) and (D) (Atomic mass of N = 14, O = 16, Cu = 63).

(I)   1 molecule of oxygen

(II)  1 atom of nitrogen

(III) 1 × 10–10 gm molecular weight of oxygen

(IV) 1 × 10–10 gm atomic weight of copper

(A) (II) <  (I) < (III) < (IV)

(B) (IV) < (III) < (II) < (I)

(C) (II) < (III) < (I) < (IV)

(D) (III) < (IV) < (I) < (II)

Sol: (i) 1 Molecule of O2 $\large = \frac{32}{6.023 \times 10^{23}}$

= 0.5 × 10-23 gm

(ii) 1 atom of N $\large = \frac{14}{6.023 \times 10^{23}}$

= 2.3 × 10-23 gm

(iii) 10–10 gm mol wt. of oxygen = 10–10 × 32 = 3.2 × 10–9 gm

(iv) 10–10 gm atom of copper = 10–10 × 63 = 6.3 × 10–9 gm

Ans: (A)