The Concentration of Carbon Monoxide in a Sample of Air

The concentration of carbon monoxide in a sample of air is 9.2 ppm. There are molecules of CO in 1.00 L of this air at 755 torr and 23°C.

A) 2.9 × 10¹⁸
B) 1.7 × 10²⁰
C) 2.3 × 10¹⁷
D) 3.8 × 10^{- 7}
E) 2.2 × 10²¹