Answer:
The correct option is: B. 366 torr
Explanation:
Given: On the ground- Initial Volume: Vâ = 8.00 mÂł, Initial Atmospheric Pressure: Pâ= 768 torr;
At 4200 m height- Final Volume: Vâ = 16.80 mÂł, Final Atmospheric Pressure: Pâ = ?
Amount of gas: n, and Temperature: T = constant
According to the Boyle's Law, for a given amount of gas at constant temperature: Â Â Â Â Pâ Vâ = Pâ Vâ
â  Pâ = Pâ Vâ á Vâ
â  Pâ = [(768 torr) Ă (8.00 mÂł)] á (16.80 mÂł)
â Â Pâ = 365.71 torr â 366 torr
Therefore, the final air pressure at 4200 m height: Pâ = 366 torr.