Concept:Heating a gas increases the kinetic energy of its particles, which weakens the attractions between them.
Explanation:When a gas is heated, its particles gain kinetic energy and move faster.
This increased motion makes the particles spread farther apart.
As the distance between particles increases, the intermolecular forces of attraction become weaker.
Thus, heating a gas causes a decrease in intermolecular forces.
The gas does not melt or sublime on heating, and its volume generally increases, not decreases.
Answer:D. decrease in intermolecular forces