The position of elements A, B, C, D and E in the periodic table are shown below:

Group 1	Group 2	Group 17	Group 18
–	–	–	D
–	B	C	–
A	–	–	E

(a) State which are metals, non-metals and noble gas in this table.

(b) State which is the most reactive (i) metal (ii) non-metal.

(c) Which type of ion will be formed by element A, B and C.

(d) Which is larger in size (i) D or E (ii) B or C.

(a) Metals — A and B, as they belong to alkali metals group and alkaline earth metals group.

Non-metals — C, as it belongs to halogen group 17.

Noble gases — D and E, as they belong to group 18 or zero group.

(b) A is the most reactive metal as Group 1 (Alkali metals) elements are very reactive and the degree of reactivity further increases down the group. C is the most reactive non-metal as it is in Group 17 (Halogens) and the degree of reactivity of halogens decreases down the group.

(c) Type of ion formed by elements A, B and C will be:

1. Element A will lose the one valence electron and become an electropositive ion [i.e., cation A⁺].
2. Element B will lose two valence electrons and become an electropositive ion [i.e., cation B²⁺].
3. Element C will gain one electron, complete its octet and become an electronegative ion [i.e., anion C^-].

(d) Larger in size

1. E is larger in size as the number of shells increases as we move down a group increasing the size of the atom.
2. B is larger in size as atomic size decreases on moving from left to right across a period due to increase in nuclear charge.