The atomic numbers of the elements Na, Mg, K and Ca are 11, 12, 19 and 20 respectively. The elements having the largest atomic radius is:

The element which has the maximum number of valence electrons is:

The correct increasing order of the atomic radii of the elements oxygen, fluorine and nitrogen is:

Which of the following are the correct characteristics of isotopes of an element?

(i) same atomic mass

(ii) same atomic number

(iii) same physical properties

(iv) same chemical properties

The correct formula of the oxide of Eka-aluminium element predicted by Mendeleev was: