Give reasons for the following:

Atomic size of an element depends on the nuclear charge of that element.

Give reasons for the following:

Down a group electronegativity should increase with increase in nuclear charge but it is seen that the electronegativity decreases.

Give reasons for the following:

If combining atoms have nearly similar electro­negativities the bond between them is covalent.

Arrange the following elements as per the guidelines in brackets.

1. Na, Cl, Mg, P [in decreasing order of atomic size]
2. C, Li, F, N [in increasing order of electronegativity]
3. Cl, Al, Na, S [in increasing order of ionization potential]
4. Li, F, C, O [in increasing order of electron affinity]
5. Ar, He, Ne [in increasing order of number of electron shells]