Match List-$I$ with List-$\mathrm{II}$. List-$I$ Electronic configuration of elements List-$\mathrm{II}$ ${\Delta }_{i}H$ in $\mathrm{kJ}{\mathrm{mol}}^{-1}$ $(a)$ $1{s}^{2}2{s}^{2}$ $(p)$ $801$ $(b)$ $1{s}^{2}2{s}^{2}2{p}^{4}$ $(q)$ $899$ $(c)$ $1{s}^{2}2{s}^{2}2{p}^{3}$ $(r)$ $1314$ $(d)$ $1{s}^{2}2{s}^{2}2{p}^{1}$ $(s)$ $1402$ Choose the most appropriate answer from the options given below:

JEE Main 2021 — Chemistry Inorganic Chemistry

2021mcqeasy

Match List- $I$ with List- $\mathrm{II}$ .

	List- $I$ Electronic configuration of elements		List- $\mathrm{II}$ ${\Delta }_{i}H$ in $\mathrm{kJ}{\mathrm{mol}}^{-1}$
$(a)$	$1{s}^{2}2{s}^{2}$	$(p)$	$801$
$(b)$	$1{s}^{2}2{s}^{2}2{p}^{4}$	$(q)$	$899$
$(c)$	$1{s}^{2}2{s}^{2}2{p}^{3}$	$(r)$	$1314$
$(d)$	$1{s}^{2}2{s}^{2}2{p}^{1}$	$(s)$	$1402$

Choose the most appropriate answer from the options given below:

Official previous-year question

Held on 26 Feb 2021 · Verified 6 Jul 2026.

Options

A
$(a)\rightarrow (q),(b)\rightarrow (r),(c)\rightarrow (s),(d)\rightarrow (p)$
B
$(a)\rightarrow (p),(b)\rightarrow (r),(c)\rightarrow (s),(d)\rightarrow (q)$
C
$(a)\rightarrow (p),(b)\rightarrow (s),(c)\rightarrow (r),(d)\rightarrow (q)$
D
$(a)\rightarrow (s),(b)\rightarrow (p),(c)\rightarrow (q),(d)\rightarrow (r)$

Did you get this right?

Solution

(a) $1{s}^{2}2{s}^{2}\rightarrow \mathrm{Be}$

(b) $1{s}^{2}2{s}^{2}2{p}^{4}\rightarrow O$

(d) $1{s}^{2}2{s}^{2}2{p}^{1}\rightarrow B$

The ionization enthalpy order is $B<\mathrm{Be}<O<N$

$\mathrm{Be}$ has more $\mathrm{IE}$ compared to $B$ due to extra stability $&N$ has more $\mathrm{IE}$ compared to oxygen due to extra stability Hence,

$N\rightarrow 1402\mathrm{kJ}{\mathrm{mol}}^{-1}$

$O\rightarrow 1314\mathrm{kJ}{\mathrm{mol}}^{-1}$

$B\rightarrow 801\mathrm{kJ}{\mathrm{mol}}^{-1}$

$\mathrm{Be}\rightarrow 899\mathrm{kJ}{\mathrm{mol}}^{-1}$

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Options

$(a)\rightarrow (q),(b)\rightarrow (r),(c)\rightarrow (s),(d)\rightarrow (p)$

$(a)\rightarrow (p),(b)\rightarrow (r),(c)\rightarrow (s),(d)\rightarrow (q)$

$(a)\rightarrow (p),(b)\rightarrow (s),(c)\rightarrow (r),(d)\rightarrow (q)$

$(a)\rightarrow (s),(b)\rightarrow (p),(c)\rightarrow (q),(d)\rightarrow (r)$

Solution

(a) $1{s}^{2}2{s}^{2}\rightarrow \mathrm{Be}$

(b) $1{s}^{2}2{s}^{2}2{p}^{4}\rightarrow O$

(d) $1{s}^{2}2{s}^{2}2{p}^{1}\rightarrow B$

The ionization enthalpy order is $B<\mathrm{Be}<O<N$

$\mathrm{Be}$ has more $\mathrm{IE}$ compared to $B$ due to extra stability $&N$ has more $\mathrm{IE}$ compared to oxygen due to extra stability Hence,

$N\rightarrow 1402\mathrm{kJ}{\mathrm{mol}}^{-1}$

$O\rightarrow 1314\mathrm{kJ}{\mathrm{mol}}^{-1}$

$B\rightarrow 801\mathrm{kJ}{\mathrm{mol}}^{-1}$

$\mathrm{Be}\rightarrow 899\mathrm{kJ}{\mathrm{mol}}^{-1}$

JEE Main 2021 — Chemistry Inorganic Chemistry

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JEE Main 2021 — Chemistry Inorganic Chemistry

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