An element 'E' has the ionisation enthalpy value of 374 kJ mol-1. 'E' reacts with elements A, B, C and D with electron gain enthalpy values of −328, −349, −325 and −295 kJ mol-1, respectively. The correct order of the products EA, EB, EC and ED in terms of ionic character is :
- EB > EA > EC > ED
- EA > EB > EC > ED
- ED > EC > EA > EB
- ED > EC > EB > EA
Answer
(1) EB > EA > EC > ED
Solution
As per NCERT, formation of an ionic bond is favoured by a low ionisation enthalpy of the metal and a more negative electron gain enthalpy of the non-metal.
The cation E+ is common (ionisation enthalpy 374 kJ mol-1 in every case), so ionic character depends only on the electron gain enthalpy of A, B, C, D.
More negative egH anion formed more easily more ionic bond
egH: B (−349) < A (−328) < C (−325) < D (−295)
Ionic character: EB > EA > EC > ED
Answer: (1)