Asample of oxygen occupies 560. ml when the pressure is 800.00 mm hg. at constant temperature, what volume does the gas occupy when the pressure decreases to 700.0 mm hg?

final volume = 640 ml

Explanation:
To answer this question, we will use Boyle's law which states that:
"At constant temperature, the product of the pressure and the volume of a given mass of gas will be constant"
Thereore:
P1V1 = P2V2
800*560 = 700*V2
V2 = 640 ml

Hope this helps :)