UPSC Chemistry 2026

(a) One real gas equation is van der Waals equation \left(P + \frac{n^2 a}{V^2}\right)(V - nb) = nRT Which parameter in the above equation reflects the intermolecular force of att…

(a) The Maxwell distribution of molecular speed of a gaseous system is dN_c = 4πN ( M / (2πRT) )^{3/2} c^{2} e^{-Mc^{2}/2RT} dc (Symbols have their usual meanings) Plot ( 1/N × dN…

(a) (i) Derive the expressions of chemical potential of a component in a mixture system in terms of extensive thermodynamic properties U, H, A and G. (10 marks) (ii) Cadmium (m. p…

(a) Draw and discuss the polarographic wave obtained in the case of a dropping mercury electrode in polarography. (10 marks) (b) (i) The equilibrium A ⇌ B + C at 25 °C is subjecte…

(a) What is the de Broglie wavelength for a baseball (140 g) moving at 40 m s⁻¹? Comment on your finding. (5 marks) (b) Distinguish between cis- and trans-dichloroethylene by usin…

(a) (i) Predict the Lewis structures and geometry of the following as per VSEPR theory : (1) SO₂, (2) I₃⁻, (3) SF₄, (4) BrF₅, (5) XeF₄ (10 marks) (ii) Draw the molecular orbital d…

(a) (i) Show that ψ(x) = e^(αx) is an eigenfunction for the operator  = d^n/dx^n. What is the eigenvalue? (5 marks) (ii) The time-independent Schrödinger equation for a free part…

(a) Differentiate between T and R conformation of hemoglobin. (10 marks) (b) (i) Describe the structure and bonding in diborane. (10 marks) (ii) How are silicates classified? Pred…

(a) (i) Draw the structures of three possible geometrical isomers of [10] annulene and explain the aromaticity. (5 marks) (ii) Explain the aromaticity of sydnone and tropolone. (5…

In the following reaction, intermediate [A] is formed : CHCl₃ + ᵗBuOK ——> [A] (a) Write the structures of the major products M, N, O, P and Q formed in the following reaction sequ…

(a) (i) Write the structure of the major products of the following reaction and write the mechanism of their formation : O O ‖ ‖ H₃C – C – H + H – C – H ──aq. NaOH──► (excess) (5…

(a) (i) Write the structure of the stereochemical product formed in the reaction of (2E, 4E)-hexa-2,4-diene under photochemical conditions and explain using the FMO approach. (10…

(a) Proteins are dynamic molecules rather than static structures. Explain this phenomenon using hemoglobin as an example. (10 marks) (b) Write the structure of the major product i…

(a) Write the structures of the products formed in the following reactions : 2×5=10 (i) (Cyclohex-2-en-1-one) —NaBH4/CeCl3, MeOH→ (ii) (Cyclohex-2-en-1-one) —Na/NH3 (l)→ (iii) Me–…

(a) (i) What are the phenomena that result in the emission wavelength being longer than the excitation wavelength in photochemical reactions ? (5 marks) (ii) Why is phosphorescenc…

(a) (i) Calculate the rotational constant of a diatomic molecule if the moment of inertia is 13·97 × 10⁻⁴⁷ kg m². (Given : Planck's constant h = 6·626 × 10⁻³⁴ Js and velocity of l…