Which of the following statements is true about energy quantization at the atomic level?
electrons can be present at any location inside the electron cloud.
electrons are present in distinct energy levels around the nucleus.
electrons are present in the free space in between two energy levels.
electrons prefer to be present as far away from the nucleus as possible.

i don't have a answer as well because i am taking the test, but i believe that is B

When you climb a ladder, your potential energy changes depending on your position in relation to the ground.

The higher you climb, the farther you can fall.

This can be compared to the orbits of Bohr's model. Each orbit has its own small, definite amount of potential energy; scientists say that this energy is quantized.

As an electron falls, energy equal to the difference between the two orbits is emitted in the form of light.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.