UPSC Chemistry 2021

(a) Calculate ⟨x⟩, the expectation value of position of a particle, in the ground state of one-dimensional box having length from 0 to l. (10 marks) (b) The enthalpy of formation…

(a) Hydrogen atoms are observed to have radiative transitions from n = 101 to n = 100 to occur. (i) What are the frequency and wavelength of the radiation emitted in this transiti…

(a) A drop of water, 0·4 cm in radius, is split up into 125 tiny drops. Find the increase in surface energy. [γwater (surface tension of water) = 72 dynes/cm ] (10 marks) (b) What…

(a) Calculate the e.m.f. of the following electrochemical cell at 25 °C : Pt/H₂₍₁ ₐₜₘ₎|H⁺₍C=0.01 M₎‖Cu²⁺₍C=0.1 M₎|Cu(s) (10 marks) (b) (i) A certain closed cell foam used as an in…

(a) Derive an equation for rate constant of a zero-order reaction. Show that half-life period of the reaction is proportional to the initial concentration of reactant. (10 marks)…

(a) How does the bonding in cyclic phosphazene differ from that of benzene and borazine? (10 marks) (b) What are the limitations of collision theory? How is it explained by transi…

(a) Draw the structures of various iron-sulphur proteins and their corresponding redox states. (10 marks) (b) How would you account for bonding in the following fluxional molecule…

(a) Justify that the interhalogen compound BrF₃ acts as an aprotic solvent and undergoes acid-base and neutralization reactions by giving examples. (10 marks) (b) The observed mag…

(a) In the reaction R—COO⁻ + Br—CN → R—CN + Br⁻ + CO₂↑ What is the origin of —CN group in the product ? Explain by using isotopic labelling technique. 10 marks (b) Discuss the pro…

(a) Involving the stereochemical concept, compare the elimination behaviour of compounds A and B in the presence of base. Also give the product(s) of the reactions. 20 marks (b) (…

(a) Complete the following reactions with mechanisms: (i) Conc. H₂SO₄ (10 marks) (ii) EtO⁻ (10 marks) (b) (i) Write the structure of the reaction product between 3-chlorocycloprop…

(a) (i) Heating of 3-deuteroindene causes scrambling of the deuterium. Explain with mechanism. (20 marks) (ii) Write the structure of product(s) formed during the thermal reaction…

(a) 2,4-Pentadione exhibits five signal in ¹H NMR spectrum. Account for the observation. Also write the approximate chemical shift. (10 marks) (b) (i) Arrange the above monomers i…

(a)(i) The molecule obtained on treatment of acetone with dilute sodium hydroxide exhibits the following spectral data. Propose the structure of this molecule. IR : 1620 cm⁻¹ and…

7.(a) Complete the above reaction sequence by writing the structures of A, B and C. I. C₆H₅—CH = CH₂ n-BuLi A 1,3-butadiene B H₂O C (excess) II. [diagram] NH₂OH A 55% H₂SO₄ B Δ C…

8.(a) (i) Write the products X/Y in the above chemical transformations. I. MCPBA → X II. OsO₄ → X NaIO₄ → Y III. OH | H₃C—CH—COOH BH₃/THF X IV. CrO₃-Pyridine CH₂Cl₂ X (ii) Predict…