Question

An element is placed in 2nd group and 3rd period of the periodic table burns in the presence of oxygen to form a basic oxide.

Identify the element :

• A. Magnesium (Mg)
• B. Calcium (Ca)
• C. Sodium (Na)
• D. Potassium (K)

Answer 1

Answer: (A)

Magnesium (Mg)

As it is in the 3rd period, the outer most shell would be 3, i.e., either 3s or 3p or 3d.

As it is in the second group, it will have two electrons in the third shell, i.e., $1s^{2}2s^{2}2p^{6}3s^2$. Hence, it has 12 electrons that is magnesium.

Hence the correct option is A.