An element ‘M' has 50% of the electrons filled in the 3rd shell as in the 2nd shell. The atomic number of ‘M’ is:
(a) 10
(b) 12
(c) 14
(d) 18
Answer:
(c) The maximum number of electrons that can be filled in the second shell = 8
Since shell 3 has 50% of electrons present in shell 2,
Number of electrons in shell 3 = 50/100 of 8 = 4
Shell can have a maximum of 2 electrons.
So, the electronic configuration of the element= 2,8,4
Atomic number = 2+8+4 = 14