Sodium (located in the third period of the periodic table) has a principle quantum
number (n) of

3

Explanation: For example, sodium is in the third period of the table, so its principal quantum number is 3. Denote the principal quantum number as n and the second number, shape, is anywhere from 0 to n-1. So for sodium, the second quantum numbers are 0,1 and 2.

whats the meaning of /

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e