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

Which of the following is the valence shell for the elements of second period of the modern periodic table?

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

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:

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