Question

In the long form of periodic table, the total number of period is:

• A. 5
• B. 7
• C. 8
• D. 9

Answer 1

The correct option is B 7

A period is a horizontal row of the periodic table.

There are seven periods in the periodic table, with each one beginning at the far left.

A new period begins when a new principal energy level begins filling with electrons.

Eg. Period $1$ has only two elements (hydrogen and helium),

while periods $2$ and $3$ have $8$ elements.