The first ionisation energy `(IE_1)` and second ionisation energy `(IE_2)` of elements X, Y and Z are given below.

Which one of the above elements is the most reactive metal, the least reactive metal and a noble gas?

Explanation

Noble gases: Ioniation energy ranging from `2372 KJmol^(-1)` to `1037 kJ mol^(-1)`. For element X, the `IE_1` value is in the range of noble gas, moreover for this element both `IE_1` and `IE_2` are higher and hence X is the noble gas. For Y, the first ionisation energy is low and second ionisation energy is very high and hence Y is most reactive metal.
For Z, both `IE_1` and `IE_2` are higher and hence it is least reactive.