Answer: The black ball will have more mass than the white ball.
Explanation: Density of a substance is defined as the ratio of mass and volume occupied by the substance.
Mathematically,

We are given that the two balls are of same size, which means that the volume of both the balls are same. We are also given that the black ball is more dense than the white ball, which means that the black ball will have more mass.
As, 
The sample with the lowest AVERAGE kinetic energy is
the coolest one.
The sample with the lowest TOTAL kinetic energy depends on
not only the temperature of the samples, but also on their size,
since each molecule in the sample has kinetic energy.
Answer:
3)Some gas molecules move further apart and some move closer together.
Explanation:
because When more gas particles enter a container, there is less space for the particles to spread out, and they become compressed. The particles exert more force on the interior volume of the container. This force is called pressure. There are several units used to express pressure.