With an isothermal increase of 3 times the gas pressure, its volume decreased by 60 ml.

With an isothermal increase of 3 times the gas pressure, its volume decreased by 60 ml. Find the initial gas volume in ml.

For an isothermal process (T = const), the following relation will be true:
Р1 * V1 = P2 * V2, where Р1 – initial gas pressure, V1 – initial gas volume, P2 – final gas pressure, V2 – final gas volume.
From the conditions of the problem:
P2 = 3P1, V2 = V1 – 60.
Let’s express and calculate the initial gas volume:
P1 * V1 = 3P1 * (V1 – 60).
V1 = 3V1 – 180.
2V1 = 180.
V1 = 90 ml.
Answer: The original gas volume was 90 ml.