An atom of an element (X) has it s K, L, and M shells f illed with some electrons. It reacts with sodium metal to form a compound NaX. The number of electrons in the M shell of an atom of element (X) will be

(1) 7
(2) 8
(3) 2
(4) 1

The isotope used in the treatment of cancer of .......

(1) Iodine
(2) Cobalt
(3) Carbon
(4) Hydrogen

The number of neutrons in an atom of  is

(1) 23
(2) 11
(3) 34
(4) 12

The electronic configuration of an ion M⁺²  is 2,8, 14. If its mass number is 56 the number of neutrons in its nucleus is -

(1) 30
(2) 32
(3) 34
(4) 42

The maximum number of electrons that can be accomodated in the 'L' shell of an atom is .....

(1) 2
(2) 4
(3) 8
(4) 16