Answer:
B
Explanation:
The net force is the force between action and reaction and when this forces are not the same an acceleration is spurred.
Answer:
The coupled velocity of both the blocks is 1.92 m/s.
Explanation:
Given that,
Mass of block A, 
Initial speed of block A, 
Mass of block B, 
Initial speed of block B, 
It is mentioned that if the two blocks couple together after collision. We need to find the common velocity immediately after collision. We know that due to coupling, it becomes the case of inelastic collision. Using the conservation of linear momentum. Let V is the coupled velocity of both the blocks. So,

So, the coupled velocity of both the blocks is 1.92 m/s. Hence, this is the required solution.
Yeah, it's every state. Atoms need a certain quanta of energy to jump to each state of energy, and therefore change state depending on how much energy is absorbed and/or released. This applies to all states of matter.
Its a, metal is a good conductor of heat so yea
Hope this helps :)