JEE MAIN - Chemistry (2025 - 23rd January Evening Shift)

1
pH of water is 7 at $25^{\circ} \mathrm{C}$. If water is heated to $80^{\circ} \mathrm{C}$., it's pH will :
Answer
(A)
Decrease
2
When a non-volatile solute is added to the solvent, the vapour pressure of the solvent decreases by 10 mm of Hg . The mole fraction of the solute in the solution is 0.2 . What would be the mole fraction of the solvent if decrease in vapour pressure is 20 mm of Hg ?
Answer
(D)
0.6
3

Match List - I with List - II

List - I List - II
(A) Bronze (I) Cu, Ni
(B) Brass (II) Fe, Cr, Ni, C
(C) UK silver coin (III) Cu, Zn
(D) Stainless steel (IV) Cu, Sn

Choose the correct answer from the options given below :

Answer
(B)
(A)-(IV), (B)-(III), (C)-(I), (D)-(II)
4
Consider a binary solution of two volatile liquid components 1 and $2 . x_1$ and $y_1$ are the mole fractions of component 1 in liquid and vapour phase, respectively. The slope and intercept of the linear plot of $\frac{1}{x_1}$ vs $\frac{1}{y_1}$ are given respectively as :
Answer
(D)
$\frac{\mathrm{P}_1^0}{\mathrm{P}_2^0}, \frac{\mathrm{P}_2^0-\mathrm{P}_1^0}{\mathrm{P}_2^0}$
5
Given below are the atomic numbers of some group 14 elements. The atomic number of the element with lowest melting point is :
Answer
(B)
50
6

Given below are two statements :

Statement (I) : The boiling points of alcohols and phenols increase with increase in the number of C -atoms.

Statement (II) : The boiling points of alcohols and phenols are higher in comparison to other class of compounds such as ethers, haloalkanes.

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

Answer
(B)
Both Statement I and Statement II are true
7
The $\alpha$-Helix and $\beta$ - Pleated sheet structures of protein are associated with its :
Answer
(D)
secondary structure
8

The effect of temperature on spontaneity of reactions are represented as :

$\Delta$H $\Delta$S Temperature Spontaneity
(A) $+$ $-$ any T Non spontaneous
(B) $+$ $+$ low T spontaneous
(C) $-$ $-$ low T Non spontaneous
(D) $-$ $+$ any T spontaneous

The incorrect combinations are :

Answer
(D)
(B) and (C) only
9

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 2 English 1 (I) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 2 English 2
(B) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 2 English 3 (II) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 2 English 4
(C) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 2 English 5 (III) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 2 English 6
(D) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 2 English 7 (IV) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Hydrocarbons Question 2 English 8

Choose the correct answer from the options given below :

Answer
(A)
(A) $-(\mathrm{III}),(\mathrm{B})-(\mathrm{IV}),(\mathrm{C})-(\mathrm{I}),(\mathrm{D})-$ (II)
10

Identify the products [A] and [B], respectively in the following reaction:

JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Haloalkanes and Haloarenes Question 7 English

Answer
(B)
JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Haloalkanes and Haloarenes Question 7 English Option 2
11
Which of the following graphs most appropriately represents a zero order reaction?
Answer
(B)
JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Chemical Kinetics and Nuclear Chemistry Question 5 English Option 2
12

Identify the coordination complexes in which the central metal ion has $\mathrm{d}^4$ configuration.

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

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

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

(D) JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Coordination Compounds Question 4 English (E) $\left[\mathrm{NiF}_6\right]^{2-}$

Choose the correct answer from the options given below :

Answer
(D)
(B) and (D) only
13

Identify A, B and C in the given below reaction sequence

JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Salt Analysis Question 3 English

Answer
(C)
$\mathrm{PbS}, \mathrm{PbSO}_4, \mathrm{PbCrO}_4$
14

Standard electrode potentials for a few half cells are mentioned below :

$$\begin{aligned} & \mathrm{E}_{\mathrm{Cu}^{2+} / \mathrm{Cu}}^{\circ}=0.34 \mathrm{~V}, \mathrm{E}_{\mathrm{Zn}^{2+} / \mathrm{Zn}}^{\circ}=-0.76 \mathrm{~V} \\ & \mathrm{E}_{\mathrm{Ag}^{+} / \mathrm{Ag}}^{\circ}=0.80 \mathrm{~V}, \mathrm{E}_{\mathrm{Mg}^{2+} / \mathrm{Mg}}^{\circ}=-2.37 \mathrm{~V} \end{aligned}$$

Which one of the following cells gives the most negative value of $\Delta \mathrm{G}^{\circ}$ ?

Answer
(A)
$\mathrm{Zn}\left|\mathrm{Zn}^{2+}(1 \mathrm{M}) \| \mathrm{Ag}^{+}(1 \mathrm{M})\right| \mathrm{Ag}$
15

Consider the reaction

$$\mathrm{X}_2 \mathrm{Y}(\mathrm{~g}) \rightleftharpoons \mathrm{X}_2(\mathrm{~g})+\frac{1}{2} \mathrm{Y}_2(\mathrm{~g})$$

The equation representing correct relationship between the degree of dissociation (x) of $\mathrm{X}_2 \mathrm{Y}(\mathrm{g})$ with its equilibrium constant Kp is __________.

Assume $x$ to be very very small.

Answer
(C)
$x=\sqrt[3]{\frac{2 \mathrm{Kp}^2}{\mathrm{p}}}$
16

Given below are two statements :

Statement (I) : For a given shell, the total number of allowed orbitals is given by $n^2$.

Statement (II) : For any subshell, the spatial orientation of the orbitals is given by $-l$ to $+l$ values including zero.

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

Answer
(A)
Both Statement I and Statement II are true
17

The ascending order of relative rate of solvolysis of following compounds is :

JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Haloalkanes and Haloarenes Question 6 English

Answer
(B)
$(\mathrm{D})<(\mathrm{A})<(\mathrm{B})<(\mathrm{C})$
18

Given below are two statements about X-ray spectra of elements :

Statement (I) : A plot of $\sqrt{v}$ ( $v=$ frequency of X-rays emitted) vs atomic mass is a straight line.

Statement (II) : A plot of $v(\nu=$ frequency of $X$-rays emitted) vs atomic number is a straight line. In the light of the above statements, choose the correct answer from the options given below :

Answer
(D)
Both Statement I and Statement II are false
19

Consider the following reactions

$$\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7 \xrightarrow[-\mathrm{H}_2 \mathrm{O}]{\mathrm{KOH}}[\mathrm{~A}] \xrightarrow[-\mathrm{H}_2 \mathrm{O}]{\mathrm{H}_2 \mathrm{SO}_4}[\mathrm{~B}]+\mathrm{K}_2 \mathrm{SO}_4$$

The products $[A]$ and $[B]$, respectively are :

Answer
(C)
$\mathrm{K}_2 \mathrm{CrO}_4$ and $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$
20

Given below are two statements:

Consider the following reaction

JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 7 English 1

Statement (I): In the case of formaldehyde JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 7 English 2 is about 2280, due to small substituents, hydration is faster.

Statement (II) : In the case of trichloro acetaldehyde JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 7 English 3 is about 2000 due to $-$I effect of $-$Cl .

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

Answer
(B)
Both Statement I and Statement II are true
21
0.01 mole of an organic compound $(X)$ containing $10 \%$ hydrogen, on complete combustion produced $0.9 \mathrm{~g} \mathrm{H}_2 \mathrm{O}$. Molar mass of $(\mathrm{X})$ is _________ $\mathrm{g} \mathrm{~mol}^{-1}$.
Answer
100
22

The bond dissociation enthalpy of $\mathrm{X}_2 \Delta \mathrm{H}_{\text {bond }}^{\circ}$ calculated from the given data is ___________ $\mathrm{kJ} \mathrm{mol}^{-1}$. (Nearest integer)

$$\begin{aligned} & \mathrm{M}^{+} \mathrm{X}^{-}(\mathrm{s}) \rightarrow \mathrm{M}^{+}(\mathrm{g})+\mathrm{X}^{-}(\mathrm{g}) \Delta \mathrm{H}_{\text {lattice }}^{\circ}=800 \mathrm{~kJ} \mathrm{~mol}^{-1} \\ & \mathrm{M}(\mathrm{~s}) \rightarrow \mathrm{M}(\mathrm{~g}) \Delta \mathrm{H}_{\text {sub }}^{\circ}=100 \mathrm{~kJ} \mathrm{~mol}^{-1} \end{aligned}$$

$$\mathrm{M}(\mathrm{~g}) \rightarrow \mathrm{M}^{+}(\mathrm{g})+\mathrm{e}^{-}(\mathrm{g}) \Delta \mathrm{H}_{\mathrm{i}}^{\circ}=500 \mathrm{~kJ} \mathrm{~mol}^{-1}$$

$$\mathrm{X}(\mathrm{~g})+\mathrm{e}^{-}(\mathrm{g}) \rightarrow \mathrm{X}^{-}(\mathrm{g}) \Delta \mathrm{H}_{\mathrm{eg}}^{\circ}=-300 \mathrm{~kJ} \mathrm{~mol}^{-1}$$

$$\mathrm{M}(\mathrm{~s})+\frac{1}{2} \mathrm{X}_2(\mathrm{~g}) \rightarrow \mathrm{M}^{+} \mathrm{X}^{-}(\mathrm{s}) \Delta \mathrm{H}_f^{\circ}=-400 \mathrm{~kJ} \mathrm{~mol}^{-1}$$

[Given : $\mathrm{M}^{+} \mathrm{X}^{-}$is a pure ionic compound and X forms a diatomic molecule $\mathrm{X}_2$ in gaseous state]

Answer
200
23

When 81.0 g of aluminium is allowed to react with 128.0 g of oxygen gas, the mass of aluminium oxide produced in grams is ________ . (Nearest integer)

Given :

Molar mass of Al is $27.0 \mathrm{~g} \mathrm{~mol}^{-1}$

Molar mass of O is $16.0 \mathrm{~g} \mathrm{~mol}^{-1}$

Answer
153
24

Consider the following sequence of reactions.

JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Compounds Containing Nitrogen Question 3 English

Total number of $\mathrm{sp}^3$ hybridised carbon atoms in the major product C formed is _________.

Answer
4
25

A compound ' $\mathrm{X}^{\prime}$ absorbs 2 moles of hydrogen and ' X ' upon oxidation with $\mathrm{KMnO}_4 \mid \mathrm{H}^{+}$ gives

JEE Main 2025 (Online) 23rd January Evening Shift Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 8 English

The total number of $\sigma$ bonds present in the compound ' $X^{\prime}$ ' is __________.

Answer
27