A given amount of gas at 15 degrees Celsius has pressure P. What will be its temperature if the pressure becomes 3P, keeping volume constant

591°C

Explanation:

Ideal gas law says:

PV = nRT

where P is absolute pressure, V is volume, n is amount of gas in moles, R is the universal gas constant, and T is absolute temperature.

Rearranging, we can put pressure and temperature on one side:

P/T = nR/V

The amount of gas and volume of gas is held constant, so:

P/T = k

Which means:

P₁ / T₁ = P₂ / T₂

Given that P₁ = P, P₂ = 3P, and T₁ = 15°C = 288 K:

P / 288 = 3P / T₂

T₂ = 864 K

The new temperature is 864 K or 591°C.