Q1 Chemistry 2025 Gaseous State mcq QP JEE Main

At the sea level, the dry air mass percentage composition is given as nitrogen gas: 70.0 , oxygen gas: 27.0 and argon gas: 3.0 . If total pressure is 1.15 atm , then calculate the ratio of following respectively:

(i) partial pressure of nitrogen gas to partial pressure of oxygen gas

(ii) partial pressure of oxygen gas to partial pressure of argon gas

(Given: Molar mass of N, O and Ar are 14, 16 and $40 \mathrm{~g} \mathrm{~mol}^{-1}$ respectively.)

A $5.46,17.8$
B $2.96,11.2$
C $4.26,19.3$
D $2.59,11.85$
Answer: B
Explanation:

Partial Pressure Ratio of Nitrogen to Oxygen :

The partial pressure of a gas is calculated using its mole fraction. The mole fraction is the ratio of the number of moles of the gas to the total number of moles of all gases.

For nitrogen ($ \text{N}_2 $), the mole fraction $\frac{n_{\text{N}_2}}{n_{\text{N}_2} + n_{\text{O}_2} + n_{\text{Ar}}}$ can be simplified as $\frac{70/28}{70/28 + 27/32 + 3/40}$.

For oxygen ($ \text{O}_2 $), the mole fraction is $\frac{27/32}{70/28 + 27/32 + 3/40}$.

Therefore, the ratio of the partial pressure of nitrogen to oxygen is :

$ \frac{P_{\text{N}_2}}{P_{\text{O}_2}} = \frac{\text{mole fraction of } \text{N}_2}{\text{mole fraction of } \text{O}_2} = \frac{70/28}{27/32} = 2.96 $

Partial Pressure Ratio of Oxygen to Argon :

For argon ($ \text{Ar} $), the mole fraction is $\frac{3/40}{70/28 + 27/32 + 3/40}$.

The ratio of the partial pressure of oxygen to argon is :

$ \frac{P_{\text{O}_2}}{P_{\text{Ar}}} = \frac{\text{mole fraction of } \text{O}_2}{\text{mole fraction of } \text{Ar}} = \frac{27/32}{3/40} = 11.25 $

Q2 Chemistry 2025 Hydrocarbons mcq QP JEE Main

Total number of sigma (σ) _______ and pi(π) ______ bonds respectively present in hex-1-en-4-yne are:

A

14 and 3

B

11 and 3

C

13 and 3

D

3 and 13

Answer: C
Explanation:

The compound given is hex - 1 - en - 4 - yne

Structure is

JEE Main 2025 (Online) 29th January Evening Shift Chemistry - Hydrocarbons Question 18 English Explanation 1

a double bond has one $\pi$ bond and one sigma bond.

A triple bond has one $\sigma$ bond and two $\pi$ bonds.

So, the number of $\pi$ bonds $=1+2=3$

For sigma bonds, count all carbon $-$ carbon bonds and carbon $-$ hydrogen bonds except the $\pi$ bonds in double bond and triple bond.

JEE Main 2025 (Online) 29th January Evening Shift Chemistry - Hydrocarbons Question 18 English Explanation 2

The number of sigma bonds = 13

So, total number of bonds $\Rightarrow \sigma=13\quad \pi=3$

Answer : option (C) 13 and 3

Q3 Chemistry 2025 Hydrocarbons numerical QP JEE Main

Isomeric hydrocarbons → negative Baeyer’s test

(Molecular formula C_{9}H_{12})

The total number of isomers from above with four different non-aliphatic substitution sites is -

Numerical / integer type question.
Answer not available in database.
Explanation:

Molecular formula of isomeric hydrocarbon $\to C_9H_{12}$ - Negative Baeyer's test

Baeyers test is given by compounds that contain readily active carbon-carbon double bond.

So, in a negative Baeyer's test, there is no readily active c = c.

Compounds that give negative Baeyer's test are alkanes and aromatic compounds.

C$_9$H$_{12}$ compound is not an alkane

(Alkane general formula C$_n$H$_{2n+2}$)

Hydrocarbons with the formula C$_9$H$_{12}$ are considered as aromatic and isomers of substituted benzene rings.

The possible isomers of C$_9$H$_{12}$ are

JEE Main 2025 (Online) 29th January Evening Shift Chemistry - Hydrocarbons Question 17 English Explanation 1

From these, total number of the isomers with four different non-aliphatic substitution sites are 2

JEE Main 2025 (Online) 29th January Evening Shift Chemistry - Hydrocarbons Question 17 English Explanation 2 JEE Main 2025 (Online) 29th January Evening Shift Chemistry - Hydrocarbons Question 17 English Explanation 3 JEE Main 2025 (Online) 29th January Evening Shift Chemistry - Hydrocarbons Question 17 English Explanation 4
Four positions (1,2,3,4) are different. So, it contain four different non-aliphatic substitution sites. Four position (1,2,3,4) are different. So, it contain four different non-aliphatic substitution sites. Four position (1,2,3,4) are not different. So, it contain four different non-aliphatic substitution sites.

Q4 Chemistry 2025 Hydrocarbons numerical QP JEE Main

The sum of sigma (σ) and pi (π) bonds in Hex-1,3-dien-5-yne is ________.

Numerical / integer type question.
Answer not available in database.
Explanation:

The compound given is hex-1,3-dien-5-yne structure is

JEE Main 2025 (Online) 29th January Morning Shift Chemistry - Hydrocarbons Question 16 English Explanation 1

A doble bond has one $\pi$ bond and one sigma bond.

A triple bond has one sigma bond and two $\pi$ bonds.

For the one triple bond, number of $\pi$ bonds = 2

For one double bond, number of $\pi$ bond = 1

For two double bonds, number of $\pi$ bonds = 2

So, total number of $\pi$ bonds = 2 + 2 = 4

For sigma bonds, count all carbon - carbon bonds and carbon - hydrogen bonds except the $\pi$ bonds in double bonds and triple bond.

JEE Main 2025 (Online) 29th January Morning Shift Chemistry - Hydrocarbons Question 16 English Explanation 2

The total number of sigma bonds = 11

So, total number of bonds:

$\sigma=11$

$\pi=4$

Sum of $\sigma$ and $\pi$ bonds

$=11+4=15$

Q5 Chemistry 2025 Hydrocarbons mcq QP JEE Main

Given below are two statements :

Statement I : One mole of propyne reacts with excess of sodium to liberate half a mole of $\mathrm{H}_2$ gas.

Statement II : Four g of propyne reacts with $\mathrm{NaNH}_2$ to liberate $\mathrm{NH}_3$ gas which occupies 224 mL at STP.

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

A Both Statement I and Statement II are incorrect
B Statement I is incorrect but Statement II is correct
C Both Statement I and Statement II are correct
D Statement I is correct but Statement II is incorrect
Answer: D
Explanation:

Statement I

“One mole of propyne reacts with excess of sodium to liberate half a mole of $\mathrm{H}_2$ gas.”

Reaction and Stoichiometry

Propyne (terminal alkyne): $\mathrm{CH_3C \equiv CH}$.

Reaction with sodium:

$ 2\,\mathrm{CH_3C \equiv CH} \;+\; 2\,\mathrm{Na} \;\longrightarrow\; 2\,(\mathrm{CH_3C \equiv C^-Na^+}) \;+\; \mathrm{H_2}. $

From this balanced equation, 2 moles of propyne produce 1 mole of $\mathrm{H_2}$.

Hence, 1 mole of propyne will produce $\tfrac{1}{2}$ mole of $\mathrm{H_2}$.

$ \boxed{\text{Statement I is correct.}} $


Statement II

“Four grams of propyne reacts with $\mathrm{NaNH_2}$ to liberate $\mathrm{NH_3}$ gas which occupies 224 mL at STP.”

Analysis

Moles of propyne

Molecular mass of propyne ($\mathrm{C_3H_4}$):

$ 3 \times 12 + 4 \times 1 = 36 + 4 = 40\,\mathrm{g/mol}. $

Four grams of propyne is:

$ \frac{4\,\mathrm{g}}{40\,\mathrm{g/mol}} = 0.1\,\mathrm{mol}. $

Reaction with $\mathrm{NaNH_2}$

For a terminal alkyne:

$ \mathrm{CH_3C \equiv CH} \;+\; \mathrm{NaNH_2} \;\longrightarrow\; \mathrm{CH_3C \equiv C^-Na^+} \;+\; \mathrm{NH_3}. $

1 mole of propyne produces 1 mole of $\mathrm{NH_3}$.

Moles of $\mathrm{NH_3}$ produced

With $0.1\,\mathrm{mol}$ of propyne, we get $0.1\,\mathrm{mol}$ of $\mathrm{NH_3}$.

Volume of $\mathrm{NH_3}$ at STP

1 mole of any ideal gas at STP $\approx 22.4\,\mathrm{L} = 22400\,\mathrm{mL}.$

$0.1\,\mathrm{mol}$ of $\mathrm{NH_3}$ occupies $0.1 \times 22.4\,\mathrm{L} = 2.24\,\mathrm{L} = 2240\,\mathrm{mL}.$

However, Statement II says the liberated $\mathrm{NH_3}$ occupies only 224 mL at STP, which corresponds to $0.01\,\mathrm{mol}$ of $\mathrm{NH_3}$, not $0.1\,\mathrm{mol}$. Therefore, the statement’s volume is off by a factor of 10 and is thus incorrect if the reaction goes to completion in a typical way.

$ \boxed{\text{Statement II is incorrect.}} $


Conclusion

Statement I is correct.

Statement II is incorrect.

Hence, the best choice is:

$ \boxed{\text{Option D: Statement I is correct but Statement II is incorrect.}} $

Q6 Chemistry 2025 Hydrocarbons mcq QP JEE Main

When sec-butylcyclohexane reacts with bromine in the presence of sunlight, the major product is :

A JEE Main 2025 (Online) 22nd January Evening Shift Chemistry - Hydrocarbons Question 10 English Option 1
B JEE Main 2025 (Online) 22nd January Evening Shift Chemistry - Hydrocarbons Question 10 English Option 2
C JEE Main 2025 (Online) 22nd January Evening Shift Chemistry - Hydrocarbons Question 10 English Option 3
D JEE Main 2025 (Online) 22nd January Evening Shift Chemistry - Hydrocarbons Question 10 English Option 4
Answer: D
Explanation:

JEE Main 2025 (Online) 22nd January Evening Shift Chemistry - Hydrocarbons Question 10 English Explanation

Formation of more stable free radical intermediate.

Q7 Chemistry 2025 Hydrocarbons mcq QP JEE Main

The alkane from below having two secondary hydrogens is :

A 2,2,4,5-Tetramethylheptane
B 2,2,4,4-Tetramethylhexane
C 4-Ethyl-3,4-dimethyloctane
D 2,2,3,3-Tetramethylpentane
Answer: D
Explanation:

JEE Main 2025 (Online) 22nd January Evening Shift Chemistry - Hydrocarbons Question 11 English Explanation 1

JEE Main 2025 (Online) 22nd January Evening Shift Chemistry - Hydrocarbons Question 11 English Explanation 2

4-Ethyl-3,4-dimethyloctane

JEE Main 2025 (Online) 22nd January Evening Shift Chemistry - Hydrocarbons Question 11 English Explanation 3 JEE Main 2025 (Online) 22nd January Evening Shift Chemistry - Hydrocarbons Question 11 English Explanation 4
Q8 Chemistry 2025 Hydrocarbons mcq QP JEE Main

The product B formed in the following reaction sequence is:

JEE Main 2025 (Online) 28th January Evening Shift Chemistry - Hydrocarbons Question 14 English
A JEE Main 2025 (Online) 28th January Evening Shift Chemistry - Hydrocarbons Question 14 English Option 1
B JEE Main 2025 (Online) 28th January Evening Shift Chemistry - Hydrocarbons Question 14 English Option 2
C JEE Main 2025 (Online) 28th January Evening Shift Chemistry - Hydrocarbons Question 14 English Option 3
D JEE Main 2025 (Online) 28th January Evening Shift Chemistry - Hydrocarbons Question 14 English Option 4
Answer: D
Explanation:

JEE Main 2025 (Online) 28th January Evening Shift Chemistry - Hydrocarbons Question 14 English Explanation

Q9 Chemistry 2025 Hydrocarbons mcq QP JEE Main

Identify product [A], [B] and [C] in the following reaction sequence.

$\mathrm{CH}_3-\mathrm{C} \equiv \mathrm{CH} \xrightarrow[\mathrm{H}_2]{\mathrm{Pd} / \mathrm{C}}[\mathrm{A}] \xrightarrow[\text { (ii) } \mathrm{Zn}, \mathrm{H}_2 \mathrm{O}]{\text { (i) } \mathrm{O}_3}[\mathrm{~B}]+[\mathrm{C}]$

A

[A]: CH_{3}—CH=CH_{2}, [B]: CH_{3}CHO, [C]: CH_{3}CH_{2}OH

B

[A]: CH_{3}—CH=CH_{2}, [B]: CH_{3}CHO, [C]: HCHO

C

[A]: CH_{3}CH_{2}CH_{3}, [B]: CH_{3}CHO, [C]: HCHO

D JEE Main 2025 (Online) 28th January Evening Shift Chemistry - Hydrocarbons Question 13 English Option 4
Answer: B
Explanation:

JEE Main 2025 (Online) 28th January Evening Shift Chemistry - Hydrocarbons Question 13 English Explanation

Q10 Chemistry 2025 Hydrocarbons numerical QP JEE Main

The compound with molecular formula $\mathrm{C}_6 \mathrm{H}_6$, which gives only one monobromo derivative and takes up four moles of hydrogen per mole for complete hydrogenation has _________ $\pi$ electrons.

Numerical / integer type question.
Answer not available in database.
Explanation: JEE Main 2025 (Online) 22nd January Evening Shift Chemistry - Hydrocarbons Question 12 English Explanation
Q11 Chemistry 2025 Hydrocarbons mcq QP JEE Main

Match the List - I with List - II

List - I Name reaction List - II Product obtainable
(A) Swarts reaction (I) Ethyl benzene
(B) Sandmeyer's reaction (II) Ethyl iodide
(C) Wurtz Fittig reaction (III) Cyanobenzene
(D) Finkelstein reaction (IV) Ethyl fluoride

Choose the correct answer from the options given below:

A A-II, B-III, C-I, D-IV
B A-II, B-I, C-III, D-IV
C A-IV, B-I, C-III, D-II
D A-IV, B-III, C-I, D-II
Answer: D
Explanation:

LIST-i Name reaction LIST-II Product obtainable
(A) Swarts reaction (I) $\mathrm{Et}-\mathrm{I} \xrightarrow[\mathrm{DMF}]{\mathrm{KF}} \mathrm{Et}-\mathrm{F}$
(B) Sandmeyer's reaction (II) $\mathrm{PhN}_2^{\oplus} \mathrm{Cl}^{-} \xrightarrow{\mathrm{CuCN} / \mathrm{KCN}} \mathrm{PhCN}+\mathrm{N}_2$
(C) Wurtz Fittig reaction (III) $ \mathrm{Ph}-\mathrm{Cl}+\mathrm{EtCl} \xrightarrow[\text { ether }]{\mathrm{Na}} $ $ \mathrm{Ph}-\mathrm{Et}+\mathrm{Ph}-\mathrm{Ph}+\mathrm{Et}-\mathrm{Et} $
(D) Finkelstein reaction (IV) $\mathrm{Et}-\mathrm{Cl} \xrightarrow[\text { acetone }]{\mathrm{NaI}} \mathrm{Et}-\mathrm{I}+\mathrm{NaCl}$

Q12 Chemistry 2025 Hydrocarbons mcq QP JEE Main

Match List - I with List - II

List - I (Isomers of $\mathrm{C}_{10} \mathrm{H}_{14}$ ) List - II (Ozonolysis product)
(A) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 8 English 1 (I) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 8 English 2
(B) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 8 English 3 (II) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 8 English 4
(C) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 8 English 5 (III) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 8 English 6
(D) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 8 English 7 (IV) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 8 English 8

Choose the correct answer from the options given below :

A (A) $-(\mathrm{III}),(\mathrm{B})-(\mathrm{IV}),(\mathrm{C})-(\mathrm{I}),(\mathrm{D})-$ (II)
B $(\mathrm{A})-(\mathrm{I}),(\mathrm{B})-(\mathrm{IV}),(\mathrm{C})-(\mathrm{III}),(\mathrm{D})-(\mathrm{II})$
C $(\mathrm{A})-(\mathrm{III}),(\mathrm{B})-(\mathrm{II}),(\mathrm{C})-(\mathrm{I}),(\mathrm{D})-(\mathrm{IV})$
D $(\mathrm{A})-(\mathrm{II}),(\mathrm{B})-(\mathrm{II}),(\mathrm{C})-(\mathrm{I}),(\mathrm{D})-(\mathrm{IV})$
Answer: A
Explanation:

Ozonolysis product

JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 8 English Explanation

Q13 Chemistry 2025 Hydrocarbons mcq QP JEE Main

The product $(\mathrm{A})$ formed in the following reaction sequence is

JEE Main 2025 (Online) 24th January Morning Shift Chemistry - Hydrocarbons Question 7 English

A JEE Main 2025 (Online) 24th January Morning Shift Chemistry - Hydrocarbons Question 7 English Option 1
B JEE Main 2025 (Online) 24th January Morning Shift Chemistry - Hydrocarbons Question 7 English Option 2
C JEE Main 2025 (Online) 24th January Morning Shift Chemistry - Hydrocarbons Question 7 English Option 3
D JEE Main 2025 (Online) 24th January Morning Shift Chemistry - Hydrocarbons Question 7 English Option 4
Answer: C
Explanation:

JEE Main 2025 (Online) 24th January Morning Shift Chemistry - Hydrocarbons Question 7 English Explanation

Q14 Chemistry 2025 Hydrocarbons mcq QP JEE Main

The reactions which cannot be applied to prepare an alkene by elimination, are

JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Hydrocarbons Question 4 English

Choose the correct answer from the options given below:

A B & E Only
B B, C & D Only
C A, C & D Only
D B & D Only
Answer: D
Explanation:

JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Hydrocarbons Question 4 English Explanation

Option (B) and (D) reaction are not able to form alkene as a product.

Q15 Chemistry 2025 Hydrocarbons mcq QP JEE Main

Given below are two statements:

Statement I : Ozonolysis followed by treatment with $\mathrm{Zn}, \mathrm{H}_2 \mathrm{O}$ of cis-2-butene gives ethanal.

Statement II : The product obtained by ozonolysis followed by treatment with $\mathrm{Zn}, \mathrm{H}_2 \mathrm{O}$ of 3, 6-dimethyloct-4-ene has no chiral carbon atom.

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

A Statement I is false but Statement II are true
B Both Statement I and Statement II are False
C Statement I is true but Statement II is false
D Both Statement I and Statement II are true
Answer: C
Explanation:

JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Hydrocarbons Question 3 English Explanation 1

JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Hydrocarbons Question 3 English Explanation 2

St-I : Correct statement

St-II : In correct statement because product has chiral centre.

Q16 Chemistry 2025 Hydrocarbons mcq QP JEE Main

Given below are two statements :

Statement (I) : Neopentane forms only one monosubstituted derivative.

Statement (II) : Melting point of neopentane is higher than n-pentane.

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

A Statement I is incorrect but Statement II is correct
B Both Statement I and Statement II are correct
C Statement I is correct but Statement II is incorrect
D Both Statement I and Statement II are incorrect
Answer: B
Explanation:

Both Statement I and Statement II are correct.

JEE Main 2025 (Online) 2nd April Evening Shift Chemistry - Hydrocarbons Question 6 English Explanation

Q17 Chemistry 2025 Hydrocarbons mcq QP JEE Main

Match List - I with List - II.

List - I (Reaction) List - II (Name of reaction)
(A) JEE Main 2025 (Online) 2nd April Evening Shift Chemistry - Hydrocarbons Question 5 English (I) Lucas reaction
(B) $ \mathrm{ArN}_2^{+} \mathrm{X}^{-} \xrightarrow[\mathrm{HCl}]{\mathrm{Cu}} \mathrm{ArCl}+\mathrm{N}_2 \uparrow+\mathrm{CuX} $ (II) Finkelstein reaction
(C) $ \mathrm{C}_2 \mathrm{H}_5 \mathrm{Br}+\mathrm{NaI} \xrightarrow[\text { Acetone }]{\text { Dry }} \mathrm{C}_2 \mathrm{H}_5 \mathrm{I}+\mathrm{NaBr} $ (III) Fittig reaction
(D) $ \mathrm{CH}_3 \mathrm{C}(\mathrm{OH})\left(\mathrm{CH}_3\right) \mathrm{CH}_3 \xrightarrow[\mathrm{ZnCl}_2]{\mathrm{HCl}} \mathrm{CH}_3 \mathrm{C}(\mathrm{Cl})\left(\mathrm{CH}_3\right) \mathrm{CH}_3 $ (IV) Gatterman reaction

$ \text { Choose the correct answer from the options given below : } $

A (A)-(III), (B)-(II), (C)-(IV), (D)-(I)
B (A)-(IV), (B)-(III), (C)-(I), (D)-(II)
C (A)-(IV), (B)-(I), (C)-(II), (D)-(III)
D (A)-(III), (B)-(IV), (C)-(II), (D)-(I)
Answer: D
Explanation:

List - I (Reaction) List - II (Name of reaction)
A. JEE Main 2025 (Online) 2nd April Evening Shift Chemistry - Hydrocarbons Question 5 English Explanation III. Fittig reaction
B. $\mathrm{ArN}_2^{+} \mathrm{X}^{-} \xrightarrow[\mathrm{HCl}]{\mathrm{Cu}} \mathrm{ArCl}+\mathrm{N}_2 \uparrow+\mathrm{CuX}$ IV. Gatterman reaction
C. $\mathrm{C}_2 \mathrm{H}_5 \mathrm{Br}+\mathrm{NaI} \xrightarrow[\text { Acetone }]{\text { Dry }} \mathrm{C}_2 \mathrm{H}_5 \mathrm{I}+\mathrm{NaBr}$ II. Finkelstein reaction
D. $\begin{aligned} & \mathrm{CH}_3 \mathrm{C}(\mathrm{OH})\left(\mathrm{CH}_3\right) \mathrm{CH}_3 \xrightarrow[\mathrm{ZnCl}_2]{\mathrm{HCl}} \\ & \mathrm{CH}_3 \mathrm{C}(\mathrm{Cl})\left(\mathrm{CH}_3\right) \mathrm{CH}_3\end{aligned}$ IV. Lucas reaction

Q18 Chemistry 2025 Hydrocarbons mcq QP JEE Main

$ \text { Which compound would give 3-methyl-6-oxoheptanal upon ozonolysis? } $

A JEE Main 2025 (Online) 3rd April Morning Shift Chemistry - Hydrocarbons Question 2 English Option 1
B JEE Main 2025 (Online) 3rd April Morning Shift Chemistry - Hydrocarbons Question 2 English Option 2
C JEE Main 2025 (Online) 3rd April Morning Shift Chemistry - Hydrocarbons Question 2 English Option 3
D JEE Main 2025 (Online) 3rd April Morning Shift Chemistry - Hydrocarbons Question 2 English Option 4
Answer: A
Explanation:

JEE Main 2025 (Online) 3rd April Morning Shift Chemistry - Hydrocarbons Question 2 English Explanation

Q19 Chemistry 2025 Hydrocarbons mcq QP JEE Main

Predict the major product of the following reaction sequence:-

JEE Main 2025 (Online) 4th April Morning Shift Chemistry - Hydrocarbons Question 1 English

A JEE Main 2025 (Online) 4th April Morning Shift Chemistry - Hydrocarbons Question 1 English Option 1
B JEE Main 2025 (Online) 4th April Morning Shift Chemistry - Hydrocarbons Question 1 English Option 2
C JEE Main 2025 (Online) 4th April Morning Shift Chemistry - Hydrocarbons Question 1 English Option 3
D JEE Main 2025 (Online) 4th April Morning Shift Chemistry - Hydrocarbons Question 1 English Option 4
Answer: B
Explanation:

JEE Main 2025 (Online) 4th April Morning Shift Chemistry - Hydrocarbons Question 1 English Explanation

Q20 Chemistry 2025 Coordination Compounds mcq QP JEE Main

Identify the homoleptic complexes with odd number of $d$ electrons in the central metal :

(A) $\left[\mathrm{FeO}_4\right]^{2-}$

(B) $\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{3-}$

(C) $\left[\mathrm{Fe}(\mathrm{CN})_5 \mathrm{NO}\right]^{2-}$

(D) $\left[\mathrm{CoCl}_4\right]^{2-}$

(E) $\left[\mathrm{Co}\left(\mathrm{H}_2 \mathrm{O}\right)_3 \mathrm{~F}_3\right]$

Choose the correct answer from the options given below :

A

(C) and (E) only

B

(A), (B) and (D) only

C

(B) and (D) only

D

(A), (C) and (E) only

Answer: C
Explanation:

Homoleptic complexes are complexes with identical ligands attached to the central metal atom.

(A) ${[Fe{O_4}]^{2 - }}$ - Homdeptic

Central metal : Fe

IN this complex, Fe is in +6 oxidation state.

{oxidation state : $x + 4( - 2) = - 2$

$x - 8 = - 2$

$x = - 2 + 6 = + 6$

Configuration of $Fe - {d^6}{s^2}$

Configuration of $Fe( + 6) - c{l^2}$

Iron has even number of d electrons. So, it is not correct.

(B) ${[Fe{(N)_6}]^{3 - }}$ - Homoleptic

Central metal : Fe

In this complex, the oxidation state of Fe is +3

Oxidation state :

$x + 6( - 1) - 3$

$x - 6 = - 3$

$x = - 3 + 6 = + 3$

Configuration of $Fe - {d^6}{s^2}$

Configuration of $Fe( + 3) - {d^5}$

Iron has odd number of d electrons.

So, it is correct.

(C) ${[Fe{(CN)_5}NO]^{2 - }}$ - Not homoleptic

This complex has different type of ligands.

${[CoC{l_4}]^{2 - }}$ - Homoleptic

Central metal - Co

In this complex, the oxidation state of Co is +2

Oxidation state:

$x + 4( - 1) = - 2$

$x - 4 = - 2$

$x = - 2 + 4 = + 2$

Configuration of $Co - {d^7}{s^2}$

Configuration of $Co( + 2) - {d^7}$

Cobalt has odd number of d electrons.

So, it is correct.

(E) $[Co{({H_2}O)_3}{F_3}]$ - Not homoleptic,

It has different type of ligands.

Complexes B and D are homoleptic complexes with odd number of d electrons in the central metal. So, correct answer is

(B) and (D) only.