Question

The element with the atomic number $12$ belongs to ____group and _____period.

• A. IA, third
• B. IIIA, third
• C. IIA, third
• D. IIIA, second

Answer 1

Answer: (C)

IIA, third

The element with atomic number $12$ is magnesium.

The electronic configuration for Mg= $1s^2,2s^{2}2p^6,3s^2$.

There are 2 electrons in the outermost shell so it belongs to the IIA group. Mg has an outermost shell, n =3, therefore, the third period.

Hence, the correct option is C.