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