JEE Main 2025 Jan 24 Shift 1 — Chemistry

Which of the following linear combinations of atomic orbitals will lead to formation of molecular orbitals in homonuclear diatomic molecules? [Internuclear axis in z-direction]

A. $2p_z$ and $2p_x$

B. $2s$ and $2p_x$

C. $3d_{xy}$ and $3d_{x^2-y^2}$

D. $2s$ and $2p_z$

E. $2p_z$ and $3d_{x^2-y^2}$

Choose the correct answer from the options given below:

Which of the following statement is true with respect to $\mathrm{H_2O}$, $\mathrm{NH_3}$ and $\mathrm{CH_4}$ ?

A. The central atoms of all the molecules are $sp^3$ hybridized.

B. The H–O–H, H–N–H and H–C–H angles in the above molecules are 104.5°, 107.5° and 109.5°, respectively.

C. The increasing order of dipole moment is $\mathrm{CH_4 < NH_3 < H_2O}$.

D. Both $\mathrm{H_2O}$ and $\mathrm{NH_3}$ are Lewis acids and $\mathrm{CH_4}$ is a Lewis base.

E. A solution of $\mathrm{NH_3}$ in $\mathrm{H_2O}$ is basic. In this solution $\mathrm{NH_3}$ and $\mathrm{H_2O}$ act as Lowry-Bronsted acid and base respectively.

Choose the correct answer from the options given below:

Let us consider an endothermic reaction which is non-spontaneous at the freezing point of water. However, the reaction is spontaneous at boiling point of water. Choose the correct option.

Consider the given plots of vapour pressure (VP) vs temperature (T/K). Which amongst the following options is correct graphical representation showing $\Delta T_f$, depression in the freezing point of a solvent in a solution?

$\mathrm{K_{sp}}$ for $\mathrm{Cr(OH)_3}$ is $1.6 \times 10^{-30}$. What is the molar solubility of this salt in water?

For the given cell $$\mathrm{Fe^{2+}_{(aq)} + Ag^{+}_{(aq)} \to Fe^{3+}_{(aq)} + Ag_{(s)}}$$ The standard cell potential of the above reaction is Given: $\mathrm{Ag^+ + e^- \to Ag} \quad E^{\ominus} = x\ \mathrm{V}$

$\mathrm{Fe^{2+} + 2e^- \to Fe} \quad E^{\ominus} = y\ \mathrm{V}$

$\mathrm{Fe^{3+} + 3e^- \to Fe} \quad E^{\ominus} = z\ \mathrm{V}$

For a reaction, $\mathrm{N_2O_{5(g)} \to 2NO_{2(g)} + \frac{1}{2}O_{2(g)}}$ in a constant volume container, no products were present initially. The final pressure of the system when 50% of reaction gets completed is

Which of the following statements are NOT true about the periodic table?

A. The properties of elements are function of atomic weights.

B. The properties of elements are function of atomic numbers.

C. Elements having similar outer electronic configurations are arranged in same period.

D. The position of an element indicates the quantum numbers of the last filled orbital.

E. The number of elements present in a period is equal to the number of atomic orbitals present in the energy level that is being filled.

Choose the correct answer from the options given below:

The large difference in the melting and boiling points of oxygen and sulphur may be explained on the basis of -

Which of the following ions is the strongest oxidizing agent? (Atomic Number of Ce = 58, Eu = 63, Tb = 65, Lu = 71)

Preparation of potassium permanganate from $\mathrm{MnO_2}$ involves two step process in which the 1st step is a reaction with KOH and $\mathrm{KNO_3}$ to produce

One mole of the octahedral complex compound $\mathrm{Co(NH_3)_5Cl_3}$ gives 3 moles of ions on dissolution in water. One mole of the same complex reacts with excess of $\mathrm{AgNO_3}$ solution to yield two moles of $\mathrm{AgCl_{(s)}}$. The structure of the complex is:

Given below are two statements I and II.

Statement I: Dumas method is used for estimation of "Nitrogen" in an organic compound.

Statement II: In Dumas method, the organic compound is heated with concentrated $\mathrm{H_2SO_4}$ to form ammonium sulphate.

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

Which one of the carbocations from the following is most stable?

Following are the four molecules "P", "Q", "R" and "S". Which one among the four molecules will react with $\mathrm{H{-}Br_{(aq)}}$ at the fastest rate?

P = 3,6-dihydro-2H-pyran (six-membered ring with O, C=C not adjacent to O); Q = 3,4-dihydro-2H-pyran (six-membered ring with O, C=C adjacent to O); R = 1-methylcyclohexene; S = 1,2-dimethylcyclohexene

Given below are two statements:

Statement I: The conversion proceeds well in the less polar medium. $$\mathrm{CH_3-CH_2-CH_2-CH_2-Cl \xrightarrow{HO^-} CH_3-CH_2-CH_2-CH_2-OH + Cl^{(-)}}$$

Statement II: The conversion proceeds well in the more polar medium. $$\mathrm{CH_3-CH_2-CH_2-CH_2-Cl \xrightarrow{R_3N:} CH_3-CH_2-CH_2-CH_2-\overset{(+)}{N}R_3\ Cl^{(-)}}$$

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

Aman has been asked to synthesise the molecule

1-(cyclopent-1-en-1-yl)ethan-1-one — a cyclopentene ring bearing a $\mathrm{-C(=O)-CH_3}$ group on a double-bond carbon

(x). He thought of preparing this molecule by aldol condensation. He found some cyclic alkenes in his laboratory. He planned ozonolysis of an alkene to obtain a dicarbonyl compound, followed by aldol reaction to prepare "x". Predict the suitable alkene that can lead to the formation of "x":

Which of the following arrangements with respect to their reactivity in nucleophilic addition reaction is correct?

The product (A) formed in the following reaction sequence is $$\mathrm{CH_3-C\equiv CH \xrightarrow[\text{iii) } H_2/Ni]{\text{i) } Hg^{2+},\ H_2SO_4\ \ \text{ii) } HCN} (A)}$$

The carbohydrate "Ribose" present in DNA, is

A. A pentose sugar

B. present in pyranose from

C. in "D" configuration

D. a reducing sugar, when free

E. in $\alpha$–anomeric form

Choose the correct answer from the options given below:

Consider the following reaction occurring in the blast furnace: $$\mathrm{Fe_3O_{4(s)} + 4CO_{(g)} \to 3Fe_{(l)} + 4CO_{2(g)}}$$ '$x$' kg of iron is produced when $2.32 \times 10^3$ kg $\mathrm{Fe_3O_4}$ and $2.8 \times 10^2$ kg CO are brought together in the furnace. The value of '$x$' is ______. (nearest integer) {Given: molar mass of $\mathrm{Fe_3O_4}$ = 232 g mol$^{-1}$ molar mass of CO = 28 g mol$^{-1}$ molar mass of Fe = 56 g mol$^{-1}$}

Standard entropies of $\mathrm{X_2}$, $\mathrm{Y_2}$ and $\mathrm{XY_5}$ are 70, 50 and 110 J K$^{-1}$ mol$^{-1}$ respectively. The temperature in Kelvin at which the reaction $$\frac{1}{2}\mathrm{X_2} + \frac{5}{2}\mathrm{Y_2} \rightleftharpoons \mathrm{XY_5} \qquad \Delta H^{\ominus} = -35\ \mathrm{kJ\ mol^{-1}}$$ will be at equilibrium is ______ (nearest integer).

37.8 g $\mathrm{N_2O_5}$ was taken in a 1 L reaction vessel and allowed to undergo the following reaction at 500 K $$\mathrm{2N_2O_{5(g)} \rightleftharpoons 2N_2O_{4(g)} + O_{2(g)}}$$ The total pressure at equilibrium was found to be 18.65 bar. Then, $K_p$ = ______ $\times 10^{-2}$ [nearest integer]

Assume $\mathrm{N_2O_5}$ to behave ideally under these conditions.

Given: R = 0.082 bar L mol$^{-1}$ K$^{-1}$

X g of benzoic acid on reaction with aq $\mathrm{NaHCO_3}$ released $\mathrm{CO_2}$ that occupied 11.2 L volume at STP. X is ______.

Among the following cations, the number of cations which will give characteristic precipitate in their identification tests with $\mathrm{K_4[Fe(CN)_6]}$ is ______. $\mathrm{Cu^{2+},\ Fe^{3+},\ Ba^{2+},\ Ca^{2+},\ NH_4^{+},\ Mg^{2+},\ Zn^{2+}}$