In an atom the number of electrons in M-shell is equal to the number of electrons in the K and L shell. Answer the following questions.

a. Which is the outer most shell?

b. How many electrons are there in its outermost shell?

c. What is the atomic number of element?

d. Write the electronic configuration of the element.

(a) M shell.

(b) 10 electrons. K shell has 2 electrons and L shell has 8 electrons. So, as given M shell has electrons equal to the number of electrons in K and L shells. So, its 2 + 8 = 10.

(c) Atomic number is equal to total number of electrons . so total electrons is equal to electrons in K, L and M shells, i.e. 2 + 8 + 10 = 20

(d) 1s²2s²2p⁶3s²3p⁶4s² – calcium