JEE MAIN - Chemistry (2025 - 7th April Morning Shift)

1

An aqueous solution of HCl with pH 1.0 is diluted by adding equal volume of water (ignoring dissociation of water). The pH of HCl solution would

$($ Given $\log 2=0.30)$

Answer
(A)
increase to 1.3
2

A person's wound was exposed to some bacteria and then bacterial growth started to happen at the same place. The wound was later treated with some antibacterial medicine and the rate of bacterial decay(r) was found to be proportional with the square of the existing number of bacteria at any instance. Which of the following set of graphs correctly represents the 'before' and 'after' situation of the application of the medicine?

[Given: $N=$ No. of bacteria, $t=$ time, bacterial growth follows $1^{\text {st }}$ order kinetics.]

Answer
(C)
JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Chemical Kinetics and Nuclear Chemistry Question 9 English Option 3
3

Total enthalpy change for freezing of 1 mol of water at $10^{\circ} \mathrm{C}$ to ice at $-10^{\circ} \mathrm{C}$ is ________

(Given: $\Delta_{\text {fus }} \mathrm{H}=x \mathrm{~kJ} / \mathrm{mol}$

$$\begin{aligned} & \mathrm{C}_{\mathrm{p}}\left[\mathrm{H}_2 \mathrm{O}(\mathrm{l})\right]=y \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1} \\ & \mathrm{C}_{\mathrm{p}}\left[\mathrm{H}_2 \mathrm{O}(\mathrm{~s})\right]=z \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1} \end{aligned}$$

Answer
(C)
$-10(100 x+y+z)$
4

Which of the following amine (s) show (s) positive carbylamine test?

JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Compounds Containing Nitrogen Question 6 English 1

B. $\left(\mathrm{CH}_3\right)_2 \mathrm{NH}$

C. $\mathrm{CH}_3 \mathrm{NH}_2$

D. $\left(\mathrm{CH}_3\right)_3 \mathrm{~N}$

JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Compounds Containing Nitrogen Question 6 English 2

Choose the correct answer from the options given below:

Answer
(D)
A and C Only
5
Which of the following compounds is least likely to give effervescence of $\mathrm{CO}_2$ in presence of aq. $\mathrm{NaHCO}_3 ?$
Answer
(D)
JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Salt Analysis Question 4 English Option 4
6

Match the List I with List II.

List - I
Molecule/Ion
List - II
Bond pair : lone pair
(on the central atom)
(A) $\mathrm{ICl}_2^{-}$ (I) $4:2$
(B) $\mathrm{H}_2 \mathrm{O}$ (II) $4:1$
(C) $\mathrm{SO_2}$ (III) $2:3$
(D) $\mathrm{XeF_4}$ (IV) $2:2$

Choose the correct answer from the options given below:

Answer
(D)
A-III, B-IV, C-II, D-I
7
The first transition series metal ' $M$ ' has the highest enthalpy of atomisation in its series. One of its aquated ion $\left(\mathrm{M}^{\mathrm{n}+}\right)$ exists in green colour. The nature of the oxide formed by the above $\mathrm{M}^{\mathrm{n}+}$ ion is:
Answer
(A)
basic
8
The number of valence electrons present in the metal among $\mathrm{Cr}, \mathrm{Co}, \mathrm{Fe}$ and Ni which has the lowest enthalpy of atomisation is :
Answer
(B)
6
9

Which of the following is the correct IUPAC name of given organic compound (X)?

JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Basics of Organic Chemistry Question 11 English

Answer
(B)
1-Bromo-2-methylbut-2-ene
10

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.)

Answer
(B)
$2.96,11.2$
11

Given below are two statements :

Statement I : Dimethyl ether is completely soluble in water. However, diethyl ether is soluble in water to a very small extent.

Statement II : Sodium metal can be used to dry diethyl ether and not ethyl alcohol.

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

Answer
(C)
Both Statement I and Statement II are true
12

Given below are two statements :

Statement I : Mohr's salt is composed of only three types of ions-ferrous, ammonium and sulfate.

Statement II : If the molar conductance at infinite dilution for ferrous, ammonium and sulfate ions are $x_1, x_2$ and $x_3 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$, respectively then the molar conductance for Mohr's salt solution at infinite dilution would be given by $x_1+x_2+2 x_3$

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

Answer
(B)
  Statement I is true but Statement II are false
13

Given below are two statements:

Statement I: D-(+)-glucose + D-(+) fructose $\xrightarrow{-\mathrm{H}_2 \mathrm{O}}$ Sucrose

$$\text { sucrose } \xrightarrow{\text { hydrolysis }} \mathrm{D}-(+) \text { glucose }+\mathrm{D}-(+) \text { fructose }$$

Statement II: Invert sugar is formed during sucrose hydrolysis

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

Answer
(B)
Statement I is false but Statement II are true
14
JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Structure of Atom Question 6 English

Which of the following statements are correct, if the threshold frequency of caesium is $5.16 \times$ $10^{14} \mathrm{~Hz}$ ?

A. When Cs is placed inside a vacuum chamber with an ammeter connected to it and yellow light is focused on Cs , the ammeter shows the presence of current.

B. When the brightness of the yellow light is dimmed, the value of the current in the ammeter is reduced.

C. When a red light is used instead of the yellow light, the current produced is higher with respect to the yellow light.

D. When a blue light is used, the ammeter shows the formation of current.

E. When a white light is used. the ammeter shows formation of current.

Choose the correct answer from the options given below:

Answer
(C)
A, B, D and E Only
15
The group 14 elements $A$ and $B$ have the first ionisation enthalpy values of 708 and $715 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. The above values are lowest among their group members. The nature of their ions $\mathrm{A}^{2+}$ and $\mathrm{B}^{4+}$ respectively is
Answer
(D)
reducing and oxidising
16

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:

Answer
(D)
B & D Only
17
When a salt is treated with sodium hydroxide solution it gives gas X . On passing gas X through reagent Y a brown coloured precipitate is formed. X and Y respectively, are
Answer
(C)
$\mathrm{X}=\mathrm{NH}_3$ and $\mathrm{Y}=\mathrm{K}_2 \mathrm{HgI}_4+\mathrm{KOH}$
18

Reaction $\mathrm{A}(\mathrm{g}) \rightarrow 2 \mathrm{~B}(\mathrm{~g})+\mathrm{C}(\mathrm{g})$ is a first order reaction. It was started with pure A

t/min Pressure of system at time t/mm Hg
10 160
$\infty$ 240

Which of the following option is incorrect?

Answer
(D)
Rate constant of the reaction is $1.693 \mathrm{~min}^{-1}$
19
An octahedral complex having molecular composition $\mathrm{Co} \cdot 5 \mathrm{NH}_3 \cdot \mathrm{Cl}^2 . \mathrm{SO}_4$ has two isomers A and B. The solution of A gives a white precipitate with $\mathrm{AgNO}_3$ solution and the solution of B gives white precipitate with $\mathrm{BaCl}_2$ solution. The type of isomerism exhibited by the complex is,
Answer
(B)
Ionisation isomerism
20

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

Answer
(C)
Statement I is true but Statement II is false
21

An organic compound weighing 500 mg , produced 220 mg of $\mathrm{CO}_2$, on complete combustion. The percentage composition of carbon in the compound is _________ $\%$. (nearest integer)

(Given molar mass in $\mathrm{g} \mathrm{mol}^{-1}$ of $\mathrm{C}: 12, \mathrm{O}: 16$ )

Answer
12
22
The number of paramagnetic complexes among $\left[\mathrm{FeF}_6\right]^{3-},\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{3-},\left[\mathrm{Mn}(\mathrm{CN})_6\right]^{3-}$, $\left[\mathrm{Co}\left(\mathrm{C}_2 \mathrm{O}_4\right)_3\right]^{3-},\left[\mathrm{MnCl}_6\right]^{3-}$, and $\left[\mathrm{CoF}_6\right]^{3-}$, which involved $\mathrm{d}^2 \mathrm{sp}^3$ hybridization is _________.
Answer
2
23

1 Faraday electricity was passed through $\mathrm{Cu}^{2+}(1.5 \mathrm{M}, 1 \mathrm{~L}) / \mathrm{Cu}$ and 0.1 Faraday was passed through $\mathrm{Ag}^{+}(0.2 \mathrm{M}, 1 \mathrm{~L}) / \mathrm{Ag}$ electrolytic cells. After this the two cells were connected as shown below to make an electrochemical cell. The emf of the cell thus formed at 298 K is __________ mV (nearest integer)

JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Electrochemistry Question 5 English

$$\begin{aligned} \text { Given : } \mathrm{E}^{\circ} \mathrm{Cu}^{2+} / \mathrm{Cu} & =0.34 \mathrm{~V} \\\\ \mathrm{E}^{\circ} \mathrm{Ag}^{+} / \mathrm{Ag} & =0.8 \mathrm{~V} \\\\ \frac{2 \cdot 303 \mathrm{RT}}{\mathrm{~F}} & =0.06 \mathrm{~V} \end{aligned}$$

Answer
400
24
The percentage dissociation of a salt $\left(\mathrm{MX}_3\right)$ solution at given temperature (van't Hoff factor $\mathrm{i}=2$ ) is ___________ %(Nearest integer)
Answer
33
25

Thyroxine, the hormone has given below structure

JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Some Basic Concepts of Chemistry Question 11 English

The percentage of iodine in thyroxine is __________ %. (nearest integer)

(Given molar mass in $\mathrm{g} \mathrm{mol}^{-1} \mathrm{C}: 12, \mathrm{H}: 1, \mathrm{O}: 16, \mathrm{~N}: 14, \mathrm{I}: 127$ )

Answer
65