A gas occupies 525 mL at a pressure of 85.0 kPa. What would the volume of the gas be at
a pressure of 65.0 kPa?

The volume would be 689 ml (0,689 L)

Explanation:

In this case, we apply the Boyle Mariotte formula, where for a certain mass of gas at constant temperature, the pressure and temperature vary inversely proportionally (P1xV1 = P2xV2). We pass the units of pressure (kPa to atm) and volume (from ml to L).  525/1000= 0,525 L

101,325Kpa1 atm

85kPa x= (85kPa x 1 atm)/101,325Kpa=0,84 atm

65kPax= (65kPa x 1 atm)/101,325Kpa=0,64 atm

P1xV1 = P2xV2  V2= (P1xV1)/P2

V2= (0,84atm  x 0,525 L)/ 0,64 atm = 0,689 L --> 0,689 x 1000= 689 ml