There are four elements 'p','q','r' and 's' having atomic numbers Z-1,Z,Z+1 and Z+2 respectively.If the element 'q' is an inert gas, select the correct answers from the following statements. (i)'p' has most negative electron gain enthalpy in the respective period. (ii)'r' is an alkali metal (iii)'s' exists in +2 oxidation state.

There are four elements 'p','q','r' and 's' having atomic numbers Z-1,

1.	There are four elements 'p','q','r' and 's' having atomic numbers Z-1,Z,Z+1 and Z+2 respectively.If the element 'q' is an inert gas, select the correct answers from the following statements. (i)'p' has most negative electron gain enthalpy in the respective period. (ii)'r' is an alkali metal (iii)'s' exists in +2 oxidation state.
Answer» (i) and (ii) only (ii) and (III) only (i) and (iii) only (i),(ii) and (iii) Solution :As 'q' is NOBLE gas, p,r and s having atomic number Z-1,Z+1 and Z+2 should belong to halogen , alkali metal and alkaline earth metal RESPECTIVELY. As halogen has one electron less than stable noble gas configuration it has greater tendency to accept an additional electron forming anion . Alkaline earth metal having VALENCE shell configuration `ns^2` EXISTS in +2 oxidation state.