JEE MAIN - Chemistry (2025 - 24th January Evening Shift)

1
The successive 5 ionisation energies of an element are $800,2427,3658,25024$ and $32824 \mathrm{~kJ} / \mathrm{mol}$, respectively. By using the above values predict the group in which the above element is present :
Answer
(C)
Group 13
2

Match List - I with List - II.

List - I
(Transition metal ion)
List - II
(Spin only magnetic moment (B.M.))
(A) $\mathrm{Ti}^{3+}$ (I) 3.87
(B) $\mathrm{V}^{2+}$ (II) 0.00
(C) $\mathrm{Ni}^{2+}$ (III) 1.73
(D) $\mathrm{Sc}^{3+}$ (IV) 2.84

Choose the correct answer from the options given below :

Answer
(A)
$\mathrm{(A) -(III}),(\mathrm{B})-(\mathrm{I}),(\mathrm{C})-(\mathrm{IV}),(\mathrm{D})-(\mathrm{II})$
3
$$ \begin{aligned} &\text { Find the compound ' } \mathrm{A} \text { ' from the following reaction sequences. }\\ &\mathrm{A} \xrightarrow{\text { aqua-regia }} \mathrm{B} \xrightarrow[\text { (2) } \mathrm{AcOH}]{\text { (1) } \mathrm{KNO}_2 \mid \mathrm{NH}_4 \mathrm{OH}} \text { yellow ppt } \end{aligned} $$
Answer
(D)
CoS
4

$$\begin{aligned} & \mathrm{S}(\mathrm{~g})+\frac{3}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{SO}_3(\mathrm{~g})+2 x \mathrm{kcal} \\ & \mathrm{SO}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{SO}_3(\mathrm{~g})+y \mathrm{kcal} \end{aligned}$$

The heat of formation of $\mathrm{SO}_2(\mathrm{~g})$ is given by :

Answer
(C)
$y-2 x \mathrm{~kcal}$
5

The structure of the major product formed in the following reaction is :

JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Haloalkanes and Haloarenes Question 3 English

Answer
(B)
JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Haloalkanes and Haloarenes Question 3 English Option 2
6
The elemental composition of a compound is $54.2 \% \mathrm{C}, 9.2 \% \mathrm{H}$ and $36.6 \% \mathrm{O}$. If the molar mass of the compound is $132 \mathrm{~g} \mathrm{~mol}^{-1}$, the molecular formula of the compound is : [Given : The relative atomic mass of $\mathrm{C}: \mathrm{H}: \mathrm{O}=12: 1: 16$ ]
Answer
(D)
$\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_3$
7

Based on the data given below :

$$\begin{array}{ll} \mathrm{E}_{\mathrm{Cr}_2 \mathrm{O}_7^{2-} / \mathrm{Cr}^{3+}}^{\circ}=1.33 \mathrm{~V} & \mathrm{E}_{\mathrm{Cl}_2 / \mathrm{Cl}^{(-)}}^{\circ}=1.36 \mathrm{~V} \\ \mathrm{E}_{\mathrm{MnO}_4^{-} / \mathrm{Mn}^{2+}}^0=1.51 \mathrm{~V} & \mathrm{E}_{\mathrm{Cr}^{3+} / \mathrm{Cr}}^{\circ}=-0.74 \mathrm{~V} \end{array}$$

the strongest reducing agent is :

Answer
(C)
$\mathrm{Cr}$
8

For reaction

JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Compounds Containing Nitrogen Question 1 English

The correct order of set of reagents for the above conversion is :

Answer
(B)
$\mathrm{H}_2 \mathrm{SO}_4, \mathrm{Ac}_2 \mathrm{O}, \mathrm{Br}_2, \mathrm{H}_2 \mathrm{O}(\Delta), \mathrm{NaOH}$
9

Given below are two statements :

Statement (I) : The first ionization energy of Pb is greater than that of Sn .

Statement (II) : The first ionization energy of Ge is greater than that of Si .

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

Answer
(D)
Statement I is true but Statement II is false
10

Match List - I with List - II.

List - I List - II
(A) Adenine (I) JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Biomolecules Question 2 English 1
(B) Cytosine (II) JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Biomolecules Question 2 English 2
(C) Thymine (III) JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Biomolecules Question 2 English 3
(D) Uracil (IV) JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Biomolecules Question 2 English 4

Choose the correct answer from the options given below :

Answer
(B)
(A)-(III), (B)-(IV), (C)-(II), (D)-(I)
11
Which of the following mixing of 1 M base and 1 M acid leads to the largest increase in temperature?
Answer
(B)
30 mL HCl and 30 mL NaOH
12

In the given structure, number of sp and $\mathrm{sp}^2$ hybridized carbon atoms present respectively are :

JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Basics of Organic Chemistry Question 2 English

Answer
(A)
3 and 5
13
The conditions and consequence that favours the $t_{2 \mathrm{~g}}{ }^3 \mathrm{e}_{\mathrm{g}}{ }^1$ configuration in a metal complex are :
Answer
(C)
weak field ligand, high spin complex
14

For the reaction,

$$\mathrm{H}_2(\mathrm{~g})+\mathrm{I}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{HI}(\mathrm{~g})$$

Attainment of equilibrium is predicted correctly by :

Answer
(C)
JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Chemical Equilibrium Question 1 English Option 3
15

Given below are two statements :

Statement (I) : JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Chemical Kinetics and Nuclear Chemistry Question 2 English 1 is valid for first order reaction.

Statement (II) : JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Chemical Kinetics and Nuclear Chemistry Question 2 English 2 is valid for first order reaction.

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

Answer
(B)
Statement I is true but Statement II is false
16

Given below are two statements :

Statement (I) : Experimentally determined oxygen-oxygen bond lengths in the $\mathrm{O}_3$ are found to be same and the bond length is greater than that of a $\mathrm{O}=\mathrm{O}$ (double bond) but less than that of a single $(\mathrm{O}-\mathrm{O})$ bond.

Statement (II) : The strong lone pair-lone pair repulsion between oxygen atoms is solely responsible for the fact that the bond length in ozone is smaller than that of a double bond $(\mathrm{O}=\mathrm{O})$ but more than that of a single bond $(\mathrm{O}-\mathrm{O})$.

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

Answer
(C)
Statement I is true but Statement II is false
17

Match List - I with List - II.

List - I List - II
(A) JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 4 English 1 (I) Etard reaction
(B) JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 4 English 2 (II) Gatterman-Koch reaction
(C) JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 4 English 3 (III) Rosenmund reduction
(D) JEE Main 2025 (Online) 24th January Evening Shift Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 4 English 4 (IV) Stephen reaction

Choose the correct answer from the options given below :

Answer
(B)
(A)-(IV), (B)-(III), (C)-(I), (D)-(II)
18
When Ethane-1,2-diamine is added progressively to an aqueous solution of Nickel (II) chloride, the sequence of colour change observed will be:
Answer
(C)
Green $\rightarrow$ Pale Blue $\rightarrow$ Blue $\rightarrow$ Violet
19

For hydrogen atom, the orbital/s with lowest energy is/are :

(A) $\mathrm{4 s}$

(B) $3 \mathrm{p}_x$

(C) $3 \mathrm{~d}_{x^2-y^2}$

(D) $3 \mathrm{~d}_{z^2}$

(E) $4 \mathrm{p}_z$

Choose the correct answer from the options given below :

Answer
(C)
(B), (C) and (D) only
20

Identify correct statement/s :

(A) $-\mathrm{OCH}_3$ and $-\mathrm{NHCOCH}_3$ are activating group.

(B) $\quad-\mathrm{CN}$ and -OH are meta directing group.

(C) -CN and $-\mathrm{SO}_3 \mathrm{H}$ are meta directing group.

(D) Activating groups act as ortho - and para directing groups.

(E) Halides are activating groups.

Choose the correct answer from the options given below :

Answer
(A)
$(A),(C)$ and (D) only
21
Consider a complex reaction taking place in three steps with rate constants $\mathrm{k}_1, \mathrm{k}_2$ and $\mathrm{k}_3$ respectively. The overall rate constant $k$ is given by the expression $k=\sqrt{\frac{k_1 k_3}{k_2}}$. If the activation energies of the three steps are 60, 30 and $10 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively, then the overall energy of activation in $\mathrm{kJ} \mathrm{mol}^{-1}$ is _________ . (Nearest integer)
Answer
20
22
The hydrocarbon $(\mathrm{X})$ with molar mass $80 \mathrm{~g} \mathrm{~mol}^{-1}$ and $90 \%$ carbon has _______ degree of unsaturation.
Answer
3
23

In Carius method of estimation of halogen, 0.25 g of an organic compound gave 0.15 g of silver bromide ( AgBr ). The percentage of Bromine in the organic compound is ________ $\times 10^{-1} \%$ (Nearest integer).

(Given : Molar mass of Ag is 108 and Br is $80 \mathrm{~g} \mathrm{~mol}^{-1}$ )

Answer
255
24
The observed and normal molar masses of compound $\mathrm{MX}_2$ are 65.6 and 164 respectively. The percent degree of ionisation of $\mathrm{MX}_2$ is __________%. (Nearest integer)
Answer
75
25
The possible number of stereoisomers for 5-phenylpent-4-en-2-ol is ________.
Answer
4