Final answer:
When a bomb explodes in midair, its total momentum decreases and its total kinetic energy increases.
Step-by-step explanation:
The correct answer is d) Its total momentum decreases.
When a bomb explodes in midair, it breaks into countless small pieces that scatter in all directions. Since momentum is conserved in a closed system, the total momentum before the explosion must be equal to the total momentum after the explosion. However, since the pieces of the bomb move in different directions, their momenta cancel each other out, resulting in a decrease in the total momentum.
On the other hand, the kinetic energy of the system increases after the explosion. This is because the bomb's potential energy is converted into kinetic energy as it fragments and moves apart.