Question

The atomic number (Z) of an element is 25. In its ground state, how many electrons are present in the 'N' shell ?

• A. 13
• B. 2
• C. 15
• D. 3

Answer 1

Answer: (B)

2

Answer 2

Z = 25 :$1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^6\, 4s^2\, 3d^5$
Therefore, number of electrons in N-shell (or 4s-subshell) = 2.