List of top Questions asked in COMEDK UGET- 2025

Arrange the following in the decreasing order of their \(pK_a\) values.

Benzene diazonium chloride when warmed with water gives a compound, whose sodium salt when reacted with allyl bromide gives compound [X]. Identify [X].

Given that the standard enthalpy of combustion of \(C(s)\) and \(CS_2(l)\) are \(-393.3\) and \(-1108.76 \, \text{kJ/mol}\) respectively and the standard enthalpy of formation of \(CS_2\) is \(128.02 \, \text{kJ/mol}\). What is \(\Delta H_f^\circ\) of \(SO_2\)?

Which one of the following statements is correct?

Choose the correct statement.

Match the coordination compounds in Column I having the given type of hybridisation of \(M^{n+}\) ion and magnetic moment as given in Column II.

An unsaturated hydrocarbon [A] undergoes the following series of reactions. Identify [A].

Which one of the following reactions does not give the correct combination of reactants and the major products formed in the reaction?

Identify the compound which gives an optically active haloalkane on reaction with \(H_2/Ni\) on heating.

For a reaction \(X_2(l) + Y_2(g) \rightleftharpoons 2XY(g)\), the \(\Delta H^0\) and \(\Delta S^0\) are \(+29.3 \, \text{kJ/mol}\) and \(104.1 \, \text{J K}^{-1}\text{mol}^{-1}\) respectively at 298 K. Find the free energy change in kJ/mol.

An organic compound [X] reacts with \(H_2/Pd-BaSO_4\) to give compound [Y], which reduces Tollens' reagent and undergoes Cannizzaro's reaction. On rigorous oxidation of [Y] in presence of \(KMnO_4/H^+\), phthalic acid is the product obtained. What is [X]?

Arrange the following free radicals in the increasing order of their stability:

If \(X\) is a haloalkane with a single chlorine atom per molecule and the percentage of Cl is 55, what would be the number of Cl atoms present in 0.1 g of the haloalkane? Atomic mass of Cl = 35.5 g/mol

A certain orbital having 2 angular nodes and no radial nodes is:

From the given covalent compounds (A to F) identify the pair of molecules which have:
(i) Two lone pairs of electrons on the central atom.
(ii) One lone pair of electrons on the central atom.
A. \(SO_2\)
B. \(ClF_3\)
C. \(BF_3\)
D. \(BrF_5\)
E. \(XeF_4\)
F. \(SF_6\)

A current of 2.5 amperes is passed through 800 ml of 0.48 M solution of CuSO$_4$ for 1.0 hour with a current efficiency of 80%. If the volume of the solution remains unchanged, what is the final molarity of the solution?

What is the reduction potential of a half-cell consisting of a Pt electrode dipped in \(2.2M\ Fe^{2+}\) and \(0.04M\ Fe^{3+}\) solution where the reaction taking place is conversion of \(Fe^{3+}\) ions to \(Fe^{2+}\)? Given \(E^\circ(Fe^{3+}/Fe^{2+})=0.771\ V\)

Solubility product of the sparingly soluble salt \(AgBrO_3\) in aqueous medium is \(9.3 \times 10^{-10}\). Calculate the mass in gram of \(AgBrO_3\) present in \(100 \, ml\) of its saturated solution. (Molar mass of \(AgBrO_3 = 236 \, g \, mol^{-1}\))

Both reactions (i) and (ii) give the same compound \(X\) as the major product. Identify \(X\).
\[ \text{(i) } 3\text{-Methylbut-1-ene} + HCl \rightarrow X \] \[ \text{(ii) Neopentyl alcohol} + HCl \ (\text{anh. } ZnCl_2) \rightarrow X \]

Choose the incorrect statement.

Two chemical reactions of the same order have equal frequency factor value. Their activation energies differ by 26.8 kJ/mol. At 300 K if \(k_2 = xk_1\), find the value of \(x\).

Arrange the following compounds in the decreasing order of the molar conductivities of their aqueous solutions.

The concentration and percentage purity of oxalic acid can be determined by titration with \(KMnO_4\) in presence of dil. \(H_2SO_4\). Instead of dil. \(H_2SO_4\), dil. HCl cannot be used because

For a 1.0 molal solution containing the non-volatile solute urea, the elevation in boiling point is 2.0 K while the depression in freezing point in a 3.0 molal solution having the same solvent is 4.0 K. If the ratio \( \frac{K_b}{K_f} = \frac{1}{X} \), what is the value of \(X\)?

Two statements, one Assertion (A) and the other Reason (R) are given. Choose the correct option. Assertion: Compound \([X]\) reacts with hydrazine in presence of \(KOH/Glycol\) to form the product \([Y]\). Reason: Reduction reaction occurs and carbonyl group is reduced to methylene group.