JEE Main 2026 — Chemistry Inorganic Chemistry

2026mcqmedium

Given below are two statements :

Statement I : The number of compounds among SO $_2$ , SO $_3$ , SF $_4$ , SF $_6$ and H $_2$ S in which sulphur does not obey the Octet rule is $3$ .

Statement II : Among [H $_2$ O, ClF $_3$ , SF $_4$ ], [NH $_3$ , BrF $_5$ , SF $_4$ ], [BrF $_5$ , ClF $_3$ , XeF $_4$ ] and [XeF $_4$ , ClF $_3$ , H $_2$ O], the number of sets in which all the molecules have one lone pair of electrons on the central atom is $1$ .

In the light of the above statements, choose the correct answer from the options given below :

Official previous-year question

Held on 6 Apr 2026 · Verified 6 Jul 2026.

Options

A
Both Statement I and Statement II are true
B
Both Statement I and Statement II are false
C
Statement I is true but Statement II is false
D
Statement I is false but Statement II is true

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Solution

Statement I: Number of compounds in which sulphur does not follow the octet rule (from $SO_2$ , $SO_3$ , $SF_4$ , $SF_6$ and $H_2S$ ).

$SO_2$ : The formal-charge-minimised structure $O=S=O$ places $10$ electrons around sulphur (expanded octet).

$SO_3$ : With three $S=O$ double bonds, sulphur has $12$ electrons around it (expanded octet).

$SF_4$ : $4$ bond pairs $+ 1$ lone pair $= 10$ electrons around $S$ (expanded octet).

$SF_6$ : $6$ bond pairs $= 12$ electrons around $S$ (expanded octet).

$H_2S$ : $2$ bond pairs $+ 2$ lone pairs $= 8$ electrons around $S$ (obeys the octet rule).

Depending on whether formal-charge-minimised structures are used for $SO_2$ and $SO_3$ , either $2$ ( $SF_4, SF_6$ ) or $4$ ( $SO_2, SO_3, SF_4, SF_6$ ) species violate the octet rule, but the number is never $3$ .

Hence, Statement I is false.

Statement II: Among the given sets, exactly one contains only molecules having one lone pair on the central atom.

Number of lone pairs on the central atom, $\text{LP} = \dfrac{\text{valence electrons of central atom} - \text{number of bonded monovalent atoms}}{2}$ :

$H_2O$ : $\dfrac{6 - 2}{2} = 2$ lone pairs

$ClF_3$ : $\dfrac{7 - 3}{2} = 2$ lone pairs

$SF_4$ : $\dfrac{6 - 4}{2} = 1$ lone pair

$NH_3$ : $\dfrac{5 - 3}{2} = 1$ lone pair

$BrF_5$ : $\dfrac{7 - 5}{2} = 1$ lone pair

$XeF_4$ : $\dfrac{8 - 4}{2} = 2$ lone pairs

Checking the sets:

$\{H_2O\ (2),\ ClF_3\ (2),\ SF_4\ (1)\}$ : not all have $1$ lone pair.

$\{NH_3\ (1),\ BrF_5\ (1),\ SF_4\ (1)\}$ : all have exactly $1$ lone pair.

$\{BrF_5\ (1),\ ClF_3\ (2),\ XeF_4\ (2)\}$ : not all have $1$ lone pair.

$\{XeF_4\ (2),\ ClF_3\ (2),\ H_2O\ (2)\}$ : not all have $1$ lone pair.

Exactly one set satisfies the condition, so Statement II is true.

Hence, Statement I is false but Statement II is true, which corresponds to option $(4)$ .

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Solution

Statement I: Number of compounds in which sulphur does not follow the octet rule (from $SO_2$ , $SO_3$ , $SF_4$ , $SF_6$ and $H_2S$ ).

$SO_2$ : The formal-charge-minimised structure $O=S=O$ places $10$ electrons around sulphur (expanded octet).

$SO_3$ : With three $S=O$ double bonds, sulphur has $12$ electrons around it (expanded octet).

$SF_4$ : $4$ bond pairs $+ 1$ lone pair $= 10$ electrons around $S$ (expanded octet).

$SF_6$ : $6$ bond pairs $= 12$ electrons around $S$ (expanded octet).

$H_2S$ : $2$ bond pairs $+ 2$ lone pairs $= 8$ electrons around $S$ (obeys the octet rule).

Hence, Statement I is false.

Statement II: Among the given sets, exactly one contains only molecules having one lone pair on the central atom.

Number of lone pairs on the central atom, $\text{LP} = \dfrac{\text{valence electrons of central atom} - \text{number of bonded monovalent atoms}}{2}$ :

$H_2O$ : $\dfrac{6 - 2}{2} = 2$ lone pairs

$ClF_3$ : $\dfrac{7 - 3}{2} = 2$ lone pairs

$SF_4$ : $\dfrac{6 - 4}{2} = 1$ lone pair

$NH_3$ : $\dfrac{5 - 3}{2} = 1$ lone pair

$BrF_5$ : $\dfrac{7 - 5}{2} = 1$ lone pair

$XeF_4$ : $\dfrac{8 - 4}{2} = 2$ lone pairs

Checking the sets:

$\{H_2O\ (2),\ ClF_3\ (2),\ SF_4\ (1)\}$ : not all have $1$ lone pair.

$\{NH_3\ (1),\ BrF_5\ (1),\ SF_4\ (1)\}$ : all have exactly $1$ lone pair.

$\{BrF_5\ (1),\ ClF_3\ (2),\ XeF_4\ (2)\}$ : not all have $1$ lone pair.

$\{XeF_4\ (2),\ ClF_3\ (2),\ H_2O\ (2)\}$ : not all have $1$ lone pair.

Exactly one set satisfies the condition, so Statement II is true.

Hence, Statement I is false but Statement II is true, which corresponds to option $(4)$ .

JEE Main 2026 — Chemistry Inorganic Chemistry

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JEE Main 2026 — Chemistry Inorganic Chemistry

Options

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Solution

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JEE Main Inorganic Chemistry in other years

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Physical Chemistry

Organic Chemistry

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