Question

The longest period of periodic table is-

• A. First
• B. Second
• C. Fourth
• D. Sixth

Answer 1

The correct option is D

Sixth

Explanation of the correct option :

The correct is option D :

Periods represent rows in a periodic table.

There is a total of 32 elements in the sixth period, which makes it the longest period in the periodic table. It begins with Cesium (Cs) and ends at Radon (Rd). It also includes the first row of inner-transitions elements.

Explanation of the incorrect options :

Option A- First Period has 2 elements- H and He.

Option B- The Second period represents the second row that has 8 elements - Li, Be, B, C, N, O, F, and Ne

Option C- The fourth period represents the fourth row. It has a total of 18 elements from K (Atomic number 19) to Krypton (36).

The longest period of the periodic table is sixth.