Two boxes contain the same ideal gas at the same temperature. Box $1$

contains more gas than Box $2.$

$1.$ Which is true about their average kinetic energies?

A$.$ It is greater for Box $1.$

B$.$ It is the same for both.

C$.$ It is greater for Box $2.$

$2.$ Which is true about their internal energies?

A$.$ It is greater for Box $1.$

B$.$ It is the same for both.

C$.$ It is greater for Box $2.$

Box $1$ is put in contact with Box $2.$

$3.$ Which of the following is true?

A$.$ The average kinetic energy of box $1$ increases.

B$.$ The average kinetic energy of both does not change.

C$.$ The average kinetic energy of box $2$ increases.