question_answer 1)

  Match the correct ionisation enthalpies and electron gain enthalpies of the following elements :

Elements	\[\Delta {{\mathbf{H}}_{\mathbf{1}}}\]	\[\Delta {{\mathbf{H}}_{\mathbf{2}}}\]	\[{{\Delta }_{eg}}\mathbf{H}\]
(i) Most reactive non-metal	(a) 419	3051	-48
(ii) Most reactive metal	(b) 1681	3374	-328
(iii) Least reactive element	(c) 738	1451	-40
(iv) Metal forming binary halide	(d) 2372	5251	+48

Answer:

  (i - b) The most reactive non-metal is the halogen which has maximum value of electron gain enthalpy. (ii - a) The most reactive metal is the alkali metal which has minimum ionisation enthalpy. (iii - d) The least reactive element is an inert gas having high ionisation enthalpy and positive electron gain enthalpy. (iv - c) Metal forming binary halide is an alkaline earth metal.