Question

Elements X, Y, and Z have atomic numbers 6, 9, and 12 respectively. Which one has four electrons in its valence shell?

• A. X
• B. Y
• C. Z
• D. Both A and B

Answer 1

The correct option is A X

Atomic number of X is 6 and electronic configuration is: 2, 4
Atomic number of Y is 9 and electronic configuration is: 2, 7
Atomic number of Z is 12 and electronic configuration is: 2, 8, 2
Thus X has four electrons in the valence "L" shell.