Q. The atomic number of an element is 35 and its mass is 81. The number of electrons in its outermost shell is
A) 3
B) 5
C) 7
D) 9
Explanation
(c)
$35 = 1s^{2},2s^{2},2p^{6},3s^{2},3p^{6},4s^{2},3d^{10},4p^{5}$
Thus, it contains 7 electrons in 4th or outermost shell
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.