Hydrogen(H), Lithium(Li), and Sodium(Na) have ___________ electron in their outer most shells.

The maximum electron present in N-shell are ____________.

Atom consists of ________________ charged nucleus.

How many isotopes are there in hydrogen atom ?

If the element have 2 electron in its outermost shell then it is _______________ in nature.

If the element has 1 electron in its outermost shell than it is ___________ in nature.

Which of the following are isobars ?

Which of the following are correct :

(a) An isotope of iodine (I-131) is used in the treatment of goiter.

(b) An isotope of cobalt (Co-60) is used to remove brain tumours and in the treatment of cancer.

Which of the following  statement / statements are correct :

(a) We can easily separate the noble gases by finding there electronic configuration because its outermost shell is completely filled.

(b) Elements like Helium, Lithium, Krypton are noble gases.

Which of the following statement / statements are correct :

(a) Mass number is denoted by M.

(b) Number of neutrons = Mass number - atomic number

(c) Mass number of lithium is 7.