Tripura Tbse Class 12 Chemistry — Real Previous-Year Papers

The quantity of charge required to produce 1 mole of Al from Al2O3 — (a) 1F (b) 6F (c) 3F (d) 2F

The unit of the rate constant of a first order reaction is — (a) mol L^-1 S^-1 (b) S^-1 (c) L mol^-1 S^-1 (d) L² mol^-2 S^-1

Responsible for the colour of KMnO4 — (a) d-d transition (b) f-f transition (c) Charge transfer (d) s-p transition

In the complex ion [Co(en)(NH3)2Cl2]+, what is the coordination number of the central cobalt ion? (a) 5 (b) 6 (c) 7 (d) 8

CH3-C≡CH is treated with Hg2+ / H+, Δ to give a product. Identify the product formed.

Why is HCOOH more acidic than CH3COOH?

Why is acetanilide (C6H5NHCOCH3) less basic than aniline?

CH3CONH2 is treated with Br2/KOH to give X. Identify compound X. Write the name of the reaction.

Which water-soluble vitamin can be stored in our body?

Which colligative property is more acceptable for determining the molecular mass of a polymeric compound?

If acetic acid completely forms a dimer in benzene solvent, what will be the value of the van't Hoff factor?

What is activation energy?

What is the number of unpaired electrons in the complex ion [Fe(CN)6]4-?

What is Lucas reagent?

According to Crystal Field Theory, the electronic configuration of complex compound [A] is t2g⁴ eg² and that of complex compound [B] is t2g⁶ eg⁰. (a) Which of [A] and [B] is low spin? (b) What is the number of unpaired electrons present in [A] and [B]?

Between methylamine and aniline, which is more basic, and why?

Write the definitions: (a) Epimer (b) Mutarotation

The rate constant of a first order reaction is K = 5.5×10^-14 s^-1. Determine the half-life of the reaction.

Give reasons: (a) Transition elements show variable valency. (b) Transition elements and their compounds act as catalysts.

(a) What is an ambident nucleophile? (b) Write an example of the Finkelstein reaction. (c) Silver benzoate (a benzene ring bearing a -COOAg group) is treated with Br2 in CCl4 (solvent) to give A + CO2 + AgBr. Write the structural formula of product A.

(a) Distinguish between aniline and benzylamine using only a chemical test. (b) Benzenediazonium chloride (a benzene ring bearing an -N2Cl group) is treated with HBF4 to give A, and A is then treated with NaNO2/Cu powder to give B. Identify compounds A and B.

(a) What are essential and non-essential amino acids called? Give an example of each. (b) What type of bond helps provide stability to the α-helix structure of a protein?

(a) Calculate the standard Gibbs free energy (ΔG°) for the reaction: Zn(s) + 2Ag+(aq) → 2Ag(s) + Zn2+(aq). Given: E°(Zn2+/Zn) = -0.76 V and E°(Ag+/Ag) = +0.80 V. (b) Why does the conductivity of a solution decrease with increasing dilution?

(a) For the reaction 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g), if the rate of disappearance of NH3 is 3.6×10^-3 mol L^-1 S^-1, what is the rate of formation of H2O? (b) Write the Arrhenius equation (which shows the effect of temperature on the rate of a chemical reaction).

(a) Although both are tetrahedral, why is [NiCl4]2- paramagnetic while [Ni(CO)4] is diamagnetic? (b) Among the following ions, which is the most stable: [Fe(H2O)6]3+, [Fe(NH3)6]3+, [Fe(C2O4)3]3-, [FeCl6]3-?

(a) Complete the following reactions: (i) Fe2+ + Cr2O7²- + H+ → (ii) MnO4^- + C2O4²- + H+ → (b) Why is it not easy to separate a lanthanoid element from a mixture of lanthanoids? (c) Why is the magnetic moment of Co2+ greater than that of Ni2+?

(a) Give an example of a primary alcohol that reacts with Lucas reagent at room temperature. (b) Why is ether stored in a coloured/dark bottle? (c) Carry out the following conversions: (i) Phenol → Picric acid (ii) Phenol → Salicylic acid

(a) State Henry's law. (b) Dissolving 6.5 g of a solute in 100 g of water raises the boiling point of the solution by 0.37 K. Determine the molecular mass of the solute. (Kb = 1.86 K kg mol^-1) (c) What do you understand by an azeotrope?

(a) Why can formaldehyde not be prepared using the Rosenmund reduction reaction? (b) Write a short note on the H.V.Z. (Hell-Volhard-Zelinsky) reaction. (c) Among the following compounds, which has the lowest pKa value? (d) Carry out the conversion: Ethanoic acid → Propanone **OR** A light-yellow crystalline aromatic compound A, molecular formula C8H8O2, reacts with SOCl2 to give a fuming liquid B with a pungent smell, molecular formula C8H7ClO. Compound B, through Rosenmund reduction, gives compound C, molecular formula C8H8O. Compound C reduces Tollens' reagent, forms a 2,4-DNP derivative, and undergoes the Cannizzaro reaction. On strong oxidation, compound C gives 1,2-benzenedicarboxylic acid. Identify compounds A, B and C. Write the equations for the relevant reactions. (b) Carry out the conversion: Benzaldehyde → Acetophenone

(a) Write the equations for the reactions occurring at the cathode and anode during the charging of a lead storage cell (lead accumulator). (b) Using a platinum electrode, a current of 5 amperes was passed through a solution of Ni(NO3)2 for 20 minutes. What quantity of nickel will be deposited at the cathode? (c) What is a cell constant? **OR** (a) What is the relationship between the specific conductivity and molar conductivity of a solution? (b) When a current of 0.6 amperes is passed through a copper sulphate (CuSO4) solution for 40 minutes, 0.2964 g of copper is deposited. What is the electrochemical equivalent of copper? (c) Write the Nernst equation for the following cell: Mg(s) | Mg2+(0.001 M) || Cu2+(0.0001 M) | Cu(s) (d) Write the cell notation/representation for the cell corresponding to the following reaction: Cu(s) + 2Ag+(aq) → Cu2+(aq) + 2Ag(s)