Answer: Decreasing the temperature inside the container will decrease the pressure of a gas inside a closed cubical container.
Explanation:
According to Gay-Lussac's Law : 'The pressure of the gas increases with increase in temperature of the gas when volume of the gas is kept constant'.
At constant volume, pressure of the gas will decrease on decreasing the temperature or vice versa.
Decreasing the temperature inside the container will decrease the pressure of a gas inside a closed cubical container.