JEE Main 2025 Jan 28 Shift 1 — Chemistry

[Stem unrecoverable: the PDF pages carrying this question's stem are corrupted in both the English and Hindi copies. The options indicate a five-statement (A-E) multiple-select question. Option texts below are recovered from the Hindi copy.]

The molecules having square pyramidal geometry are

What is the freezing point depression constant of a solvent, 50 g of which contain 1 g non volatile solute (molar mass 256 g mol$^{-1}$) and the decrease in freezing point is 0.40 K ?

Ice and water are placed in a closed container at a pressure of 1 atm and temperature 273.15 K. If pressure of the system is increased 2 times, keeping temperature constant, then identify correct observation from following

A weak acid HA has degree of dissociation x. Which of the following options correctly explains ($\mathrm{pH} - \mathrm{p}K_a$)?

Match the LIST-I with LIST-II

	LIST-I (Redox Reaction)		LIST-II (Type of Redox Reaction)
A.	$\mathrm{CH_{4(g)} + 2O_{2(g)} \xrightarrow{\Delta} CO_{2(g)} + 2H_2O_{(l)}}$	I.	Disproportionation reaction
B.	$\mathrm{2NaH_{(s)} \xrightarrow{\Delta} 2Na_{(s)} + H_{2(g)}}$	II.	Combination reaction
C.	$\mathrm{V_2O_{5(s)} + 5Ca_{(s)} \xrightarrow{\Delta} 2V_{(s)} + 5CaO_{(s)}}$	III.	Decomposition reaction
D.	$\mathrm{2H_2O_{2(aq)} \xrightarrow{\Delta} 2H_2O_{(l)} + O_{2(g)}}$	IV.	Displacement reaction

Choose the correct answer from the options given below:

For a given reaction $\mathrm{R \to P}$, $t_{1/2}$ is related to $[\mathrm{A}]_0$ as given in table.

$[\mathrm{A}]_0/\mathrm{mol\ L^{-1}}$	$t_{1/2}/\mathrm{min}$
0.100	200
0.025	100

Given: $\log 2 = 0.30$

Which of the following is true?

A. The order of the reaction is $\frac{1}{2}$.

B. If $[\mathrm{A}]_0$ is 1M, then $t_{1/2}$ is $200\sqrt{10}$ min

C. The order of the reaction changes to 1 if the concentration of reactant changes from 0.100 M to 0.500 M.

D. $t_{1/2}$ is 800 min for $[\mathrm{A}]_0 = 1.6$ M

Choose the correct answer from the options given below:

The incorrect decreasing order of atomic radii is

Consider the following elements In, Tl, Al, Pb, Sn and Ge.

The most stable oxidation states of elements with highest and lowest first ionisation enthalpies, respectively, are

Which of the following oxidation reactions are carried out by both $\mathrm{K_2Cr_2O_7}$ and $\mathrm{KMnO_4}$ in acidic medium?

A. $\mathrm{I^- \to I_2}$

B. $\mathrm{S^{2-} \to S}$

C. $\mathrm{Fe^{2+} \to Fe^{3+}}$

D. $\mathrm{I^- \to IO_3^-}$

E. $\mathrm{S_2O_3^{2-} \to SO_4^{2-}}$

Choose the correct answer from the options given below:

Consider 'n' is the number of lone pair of electrons present in the equatorial position of the most stable structure of $\mathrm{ClF_3}$. The ions from the following with 'n' number of unpaired electrons are

A. $\mathrm{V^{3+}}$

B. $\mathrm{Ti^{3+}}$

C. $\mathrm{Cu^{2+}}$

D. $\mathrm{Ni^{2+}}$

E. $\mathrm{Ti^{2+}}$

Choose the correct answer from the options given below:

[Stem unrecoverable: the PDF page carrying this question's stem is corrupted in both the English and Hindi copies. The visible options are transition-metal ions; the first two options are images that are also unrecoverable.]

Given below are two statements:

Statement I:

$\mathrm{Et_2N{-}CH_2CH_2{-}Cl}$

will undergo alkaline hydrolysis at a faster rate than

$\mathrm{Et_2CH{-}CH_2CH_2{-}Cl}$

Statement II: In

$\mathrm{Et_2N{-}CH_2CH_2{-}Cl}$

, intramolecular substitution takes place first by involving lone pair of electrons on nitrogen.

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

The correct order of stability of following carbocations is :

A = $\mathrm{Ph_3C^{\oplus}}$ (triphenylmethyl cation); B = $\mathrm{Ph_2\overset{\oplus}{C}H}$ (diphenylmethyl cation); C = tropylium (cycloheptatrienyl) cation; D = $\mathrm{H_3C{-}CH_2{-}\overset{\oplus}{C}H{-}CH_3}$ (butan-2-ylium cation)

A molecule ("P") on treatment with acid undergoes rearrangement and gives ("Q"). ("Q") on ozonolysis followed by reflux under alkaline condition gives ("R"). The structure of ("R") is given below.

"R" = 1-(2-methylcyclopent-1-en-1-yl)ethan-1-one — a cyclopentene ring bearing a $\mathrm{COCH_3}$ group at C1 and a $\mathrm{CH_3}$ group at C2

The structure of ("P") is

The products A and B in the following reactions, respectively are

$$\mathrm{A} \xleftarrow{\mathrm{Ag{-}NO_2}} \mathrm{CH_3{-}CH_2{-}CH_2{-}Br} \xrightarrow{\mathrm{AgCN}} \mathrm{B}$$

Both acetaldehyde and acetone (individually) undergo which of the following reactions?

A. Iodoform Reaction

B. Cannizaro Reaction

C. Aldol Condensation

D. Tollen's Test

E. Clemmensen Reduction

Choose the correct answer from the options given below:

[Stem unrecoverable: the PDF pages carrying this question's stem are corrupted in both the English and Hindi copies. The options indicate a five-statement (A-E) multiple-select question. Option texts below are recovered from the Hindi copy.]

Given below are two statements:

Statement I : D-glucose pentaacetate reacts with 2, 4 - dinitrophenylhydrazine

Statement II : Starch, on heating with concentrated sulfuric acid at 100°C and 2 - 3 atmosphere pressure produces glucose.

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

Given below are two statements:

Statement I: In the oxalic acid vs $\mathrm{KMnO_4}$ (in the presence of dil $\mathrm{H_2SO_4}$) titration the solution needs to be heated initially to 60°C, but no heating is required in Ferrous ammonium sulphate (FAS) vs $\mathrm{KMnO_4}$ titration (in the presence of dil $\mathrm{H_2SO_4}$)

Statement II: In oxalic acid vs $\mathrm{KMnO_4}$ titration, the initial formation of $\mathrm{MnSO_4}$ takes place at high temperature, which then acts as catalyst for further reaction. In the case of FAS vs $\mathrm{KMnO_4}$, heating oxidizes $\mathrm{Fe^{2+}}$ into $\mathrm{Fe^{3+}}$ by oxygen of air and error may be introduced in the experiment.

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

The molarity of a 70% (mass/mass) aqueous solution of a monobasic acid (X) is _____ $\times\ 10^{-1}$ M(Nearest integer)

[Given: Density of aqueous solution of (X) is $1.25\ \mathrm{g\ mL^{-1}}$

Molar mass of the acid is $70\ \mathrm{g\ mol^{-1}}$ ]

The formation enthalpies, $\Delta H_f^{\ominus}$ for $\mathrm{H_{(g)}}$ and $\mathrm{O_{(g)}}$ are 220.0 and 250.0 $\mathrm{kJ\ mol^{-1}}$, respectively, at 298.15 K, and $\Delta H_f^{\ominus}$ for $\mathrm{H_2O_{(g)}}$ is $-242.0\ \mathrm{kJ\ mol^{-1}}$ at the same temperature. The average bond enthalpy of the $\mathrm{O{-}H}$ bond in water at 298.15 K is _______ $\mathrm{kJ\ mol^{-1}}$ (nearest integer).

Given below is the plot of the molar conductivity vs $\sqrt{\text{concentration}}$ for KCl in aqueous solution.

graph of molar conductivity $\Lambda_m\ (\mathrm{S\ cm^2\ mol^{-1}})$ vs $\sqrt{C}\ (\mathrm{mol/L})^{1/2}$ — a straight line with negative slope passing through $\Lambda_m = 150$ at $\sqrt{C} = 0.1$ and $\Lambda_m = 100$ at $\sqrt{C} = 0.15$

If, for the higher concentration of KCl solution, the resistance of the conductivity cell is 100 $\Omega$, then the resistance of the same cell with the dilute solution is 'x' $\Omega$.

The value of x is ______ (Nearest integer)

Quantitative analysis of an organic compound (X) shows following % composition.

C : 14.5 %  Cl : 64.46%

H : 1.8 %

(Empirical formula mass of the compound (X) is ____ $\times 10^{-1}$

(Given molar mass in $\mathrm{g\ mol^{-1}}$ of C : 12, H : 1, O : 16, Cl : 35.5)

Consider the following sequence of reactions:

benzene ring with Cl substituent (Chlorobenzene)

$$\text{Chlorobenzene} \xrightarrow[\substack{\text{ii) } \mathrm{CO_2, H_3O^+} \\ \text{iii) } \mathrm{NH_3},\ \Delta}]{\text{i) Mg, dry ether}} \mathrm{A} \xrightarrow{\mathrm{Br_2,\ NaOH}} \mathrm{B}$$

11.25 mg of chlorobenzene will produce ---- $\mathrm{x}10^{-1}$ mg of product B.

(Consider the reactions result in complete conversion.)

[Given molar mass of C, H, O, N and Cl as 12, 1, 16, 14 and 35.5 $\mathrm{g\ mol^{-1}}$ respectively]