Arrange the elements of second period in increasing order of their electron affinity. Name the elements which do not follow the trend in this period.

Among the elements given below, the element with least electronegativity is:

(i) Lithium (ii) Boron  (III) Carbon (iv) Fluorine 

Among the elements given below, the element with most electronegativity is:

(i) Magnesium (ii) Chlorine (iii) Aluminium (iv) Sulphur

Explain the following:

Group $17$ elements are strong non-metals, while group$1$elements are strong metals.

Explain the following:

Metallic character of elements decreases from left to right in a period while it increases in moving down a group.

Explain the following:

Halogens have high electron affinity.

Explain the following:

The reducing power of an element increases down in the group while decreases in a period.

Explain the following:

The size of atoms progressively becomes smaller when we move from sodium$\left(\mathrm{Na}\right)$ to chlorine $\left(\mathrm{Cl}\right)$ in the third period of the Periodic Table.