JEE Main 2019 — Chemistry Physical Chemistry

2019mcqmedium

The isoelectronic set of ions is:

Official previous-year question

Held on 10 Apr 2019 · Verified 6 Jul 2026.

Options

A
${F}^{-}, L{i}^{+}, N{a}^{+}$ and $M{g}^{2+}$
B
${N}^{3-}, L{i}^{+}, M{g}^{2+}$ and ${O}^{2-}$
C
${N}^{3-}, {O}^{2-}, {F}^{-}$ and $N{a}^{+}$
D
$L{i}^{+}, N{a}^{+}, {O}^{2-}$ and ${F}^{-}$

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Solution

In Isoelectronic species, number of electrons should be same

Number of electrons present in ${\text{Li}}^{\text{+}}\text{= 3}-\text{1 = 2}$

Number of electrons present in ${\text{Na}}^{\text{+}}\text{= 11}-\text{1 = }\text{10}$

(A) ${F}^{-}=9+1=10{e}^{-}$

$L{i}^{+}=3-1=2{e}^{-}$

$N{a}^{+}=11-1=10{e}^{-}$

$M{g}^{+2}=12-2=10{e}^{-}$

(B) ${N}^{-3}=7+3=10{e}^{-}$

$L{i}^{+}=3-1=2{e}^{-}$

$M{g}^{+2}=12-2=10{e}^{-}$

$N{a}^{+}=11-1=10{e}^{-}$

${\text{O}}^{\text{2}-}\text{= 8+2 = 10}$

${\text{N}}^{\text{3}-}\text{= 7+3 = 10}$

$M{g}^{2+}=12-2=10$

(d) $L{i}^{+}=3-1=2{e}^{-}$

$N{a}^{+}=11-1=10{e}^{-}$

${O}^{-2}=8+2=10{e}^{-}$

${F}^{-}=9+1=10{e}^{-}$

Hence, ${N}^{3-}, {O}^{2-}, {F}^{-}, N{a}^{+}$ are isoelectronic.

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JEE Main Physical Chemistry in other years

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JEE Main 2019 — Chemistry Physical Chemistry

2019mcqmedium

The isoelectronic set of ions is:

Official previous-year question

Held on 10 Apr 2019 · Verified 6 Jul 2026.

Options

A
${F}^{-}, L{i}^{+}, N{a}^{+}$ and $M{g}^{2+}$
B
${N}^{3-}, L{i}^{+}, M{g}^{2+}$ and ${O}^{2-}$
C
${N}^{3-}, {O}^{2-}, {F}^{-}$ and $N{a}^{+}$
D
$L{i}^{+}, N{a}^{+}, {O}^{2-}$ and ${F}^{-}$

Did you get this right?

Solution

In Isoelectronic species, number of electrons should be same

Number of electrons present in ${\text{Li}}^{\text{+}}\text{= 3}-\text{1 = 2}$

Number of electrons present in ${\text{Na}}^{\text{+}}\text{= 11}-\text{1 = }\text{10}$

(A) ${F}^{-}=9+1=10{e}^{-}$

$L{i}^{+}=3-1=2{e}^{-}$

$N{a}^{+}=11-1=10{e}^{-}$

$M{g}^{+2}=12-2=10{e}^{-}$

(B) ${N}^{-3}=7+3=10{e}^{-}$

$L{i}^{+}=3-1=2{e}^{-}$

$M{g}^{+2}=12-2=10{e}^{-}$

$N{a}^{+}=11-1=10{e}^{-}$

${\text{O}}^{\text{2}-}\text{= 8+2 = 10}$

${\text{N}}^{\text{3}-}\text{= 7+3 = 10}$

$M{g}^{2+}=12-2=10$

(d) $L{i}^{+}=3-1=2{e}^{-}$

$N{a}^{+}=11-1=10{e}^{-}$

${O}^{-2}=8+2=10{e}^{-}$

${F}^{-}=9+1=10{e}^{-}$

Hence, ${N}^{3-}, {O}^{2-}, {F}^{-}, N{a}^{+}$ are isoelectronic.

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JEE Main Physical Chemistry in other years

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JEE Main 2019 — Chemistry Physical Chemistry

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JEE Main Physical Chemistry in other years

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JEE Main 2019 — Chemistry Physical Chemistry

Options

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Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry