19: Movement of electrons from one energy level to the other is called...?

Here are the answers to your questions:

19: Movement of electrons from one energy level to the other is called...?

When an electron moves from one discrete energy level to another within an atom, it is referred to as an electron transition. This process involves the absorption or emission of energy (often as light).

The final answer is $\boxed{\text{d. Electron transition}}$.

20: Which of the following is a property of elements of Z+2?

The phrase "elements of Z+2" is likely referring to elements that tend to form ions with a +2 charge, such as the alkaline earth metals (Group 2 elements). These elements readily lose two electrons to achieve a stable electron configuration. The tendency of an atom to lose electrons and form positive ions is called electropositivity.

The final answer is $\boxed{\text{b. Electro positive}}$.