Question

112.0 mL of NO2 at STP was liquefied, the density of the liquid being 1.15 g mL–1. Calculate the volume and the number of molecules in the liquid NO2(At. wt. of N = 14)

• A. 0.10 mL and 3.01 × 1022
• B. 0.20 mL and 3.01 × 1021
• C. 0.20 mL and 6.02 × 1023
• D. 0.40 mL and 6.02 × 1021

Answer 1

Answer: (B)

0.20 mL and 3.01 × 1021

Answer 2

(2)

Mole of NO2= $\frac{112}{22400}$ = 5 × 10–3

Mass of NO2 = 5 × 10–3 × 46 = 0.23 gm

Volume of NO2 = $\frac{Mass}{Density}$ = $\frac{0.23}{1.15}$= 0.2 ml

Number of molecule = 5 × 10–3 × 6.023 × 1023 = 3.1 × 1021.