Question

The electrical configuration of an atom is 2, 8, 7.

Which of the following elements would be chemically similar to it? The atomic numbers of the elements are given in parentheses.

1. Br (35)
2. S (16)
3. Ar (18)
4. Se (34)

Answer 1

Correct Answer - Option 1 : Br (35)

The correct answer is ​Br (35).

• The electronic configuration of an atom is 2, 8, 7 so the atomic number of the element is 17.
• The element with the atomic number of 17 is Chlorine.
• Thus, chlorine and bromine belong to the same group 17 and they are called halogens.
• Br is the third-lightest halogen.
• Chlorine is the second-lightest of the halogens.