The air pressure on top of the world's tallest mountain is 253 mmHg. If the mole fraction of nitrogen gas in air is 0.7808, what is its partial pressure in mmHg at the summit of the mountain?

• A. 55.5 mmHg
• B. 98.8 mmHg
• C. 198 mmHg
• D. 253 mmHg

Answer: (C)