Gas because liquids and solids volumes don't change from switching containers.
An airplane is flying at a constant speed in a positive direction. It slows down when it approaches the airport where it's going to land. this is an example of negative acceleration (D).
Microwave<span> ovens are so quick and efficient because they channel </span>heat<span> energy directly to the molecules (tiny particles) inside </span>food<span>. </span>Microwaves heat food<span> like the sun heats your face—by radiation. A </span>microwave<span> is much like the electromagnetic waves that zap through the air from TV and radio transmitters</span>
Answer:

Explanation:
It is given that,
Initially, the electron is in n = 7 energy level. When it relaxes to a lower energy level, emitting light of 397 nm. We need to find the value of n for the level to which the electron relaxed. It can be calculate using the formula as :


R = Rydberg constant, 

Solving above equation we get the value of final n is,

or

So, it will relax in the n = 2. Hence, this is the required solution.