Question

What is the atomic number of an element having a total of 3 shells and 5 electrons in the valence shell of its atom?

• A. 3
• B. 5
• C. 15
• D. 18

Answer 1

The correct option is C 15

There are a total of 3 shells and 5 electrons in the valence shell of the atom of the element. The maximum numbers of electrons that the first and second
shell can have are 2 and 8 respectively.

Therefore, total number of electrons in the atom = 2+8+5=15

In a neutral atom, the number of protons and the number of electrons are equal. Therefore, the total number of protons is also 15.

Hence, the atomic number of the element is 15.