Q1: At a constant volume, for a fixed number of moles of a gas, the pressure of the gas increases with rise of temperature due to

ANS:C - increase in molecular attraction.

At a constant volume, for a fixed number of moles of a gas, the pressure of the gas increases with the rise of temperature due to the increase in average molecular speed. This is described by the ideal gas law: 𝑃𝑉=𝑛𝑅𝑇PV=nRT Where:

• 𝑃P is pressure
• 𝑉V is volume (which is constant in this case)
• 𝑛n is the number of moles of gas (fixed)
• 𝑅R is the gas constant
• 𝑇T is temperature

Rearranging this equation: 𝑃∝𝑇P∝T This means that pressure is directly proportional to temperature at constant volume and number of moles. When temperature increases, the average kinetic energy of the gas molecules increases, resulting in higher velocities. As a result, the molecules collide with the container walls more frequently and with greater force, leading to an increase in pressure. So, the correct option is: increase in average molecular speed.