Answer:
These energy exchanges are not changes in kinetic energy. They are changes in bonding energy between the molecules. If heat is coming into a substance during a phase change, then this energy is used to break the bonds between the molecules of the substance.
An LED is useful because when a current passes through it, it gives out light.
Answer: 1: (A) They allow electrons to move freely between them. 2: (C) they change their positions relative to one another.
Explanation:
We use the equation of motion for vertical component,
Here, 
is displacement of bullet, 
is vertical initial velocity of bullet which is equal to zero because bullet was fired horizontally, and t is time of flight.
Therefore,
Given, 
Substituting the values, we get time of flight
