CBSE 12th Chemistry Delhi Set 1 - 2023 | Class 12 Year Wise Previous Years Questions

Chemistry

1. Which of the following molecules has a chiral centre correctly labelled with an asterisk (*) ? 2. Which of the following alcohols will not undergo oxidation? 3. A voltaic cell is made by connecting two half cells represented by half equations below: $$\begin{aligned} & \mathrm{Sn} 4. Four half reactions I to IV are shown below: I. $$2 \mathrm{Cl}^{-} \rightarrow \mathrm{Cl}_2+2 \mathrm{e}^{-}$$ II. $$4 5. Which property of transition metals enables them to behave as catalysts? 6. In the two tetrahedral structures of dichromate ion 7. 1 mole of liquid A and 2 moles of liquid $$B$$ make a solution having a total vapour pressure 40 torr. The vapour pressu 8. Which of the following would not be a good choice for reducing nitrobenzene to aniline? 9. If molality of a dilute solution is doubled, the value of the molal elevation constant $$\left(\mathrm{K}_{\mathrm{b}}\r 10. Hydrolysis of sucrose is called 11. Which one of the following has lowest $$\mathrm{pK}_{\mathrm{a}}$$ value? 12. Which of the following cell was used in Apollo space programme? 13. The following experimental rate data were obtained for a reaction carried out at $$25^{\circ} \mathrm{C}$$ $$A_{(g)}+B_{ 14. The magnetic moment of $$\left[\mathrm{NiCl}_4\right]^{2-}$$ [Atomic number : $$\mathrm{Ni}=28$$ ] 15. Assertion (A): Proteins are polymers of $$\alpha$$-amino acids connected by a peptide bond. Reason (R): A tetrapeptide c 16. Assertion (A): For a zero order reaction the unit of rate constant and rate of reaction are same. Reason (R) : Rate of r 17. Assertion (A): Acetic acid but not formic acid can be halogenated in presence of red $$\mathrm{P}$$ and $$\mathrm{Cl}_2$ 18. Assertion (A): Trans $$\left[\mathrm{Cr} \mathrm{Cl}_2(\mathrm{ox})_2\right]^{3-}$$ shows optical isomerism. Reason (R): 19. (a) (i) What should be the signs (positive/ negative) for $$\mathrm{E}_{\text {Cell }}^0$$ and $$\Delta \mathrm{G}^0$$ f 20. What happens to the rate constant $$k$$ and activation energy $$E_a$$ as the temperature of a chemical reaction is incre 21. (a) Which of the following species cannot act as a ligand? Give reason. $$\mathrm{OH}^{-}, \mathrm{NH}_4^{+}, \mathrm{CH 22. Why is boiling point of o-dichlorobenzene higher than p-dichlorobenzene but melting point of para isomer is higher than 23. For the pair phenol and cyclohexanol, answer the following (a) Why is phenol more acidic than cyclohexanol? (b) Give one 24. (a) (i) Draw the zwitter ion structure for sulphanilic acid. (ii) How can the activating effect of $$-\mathrm{NH}_2$$ gr 25. Give the reaction of glucose with hydrogen cyanide. Presence of which group is confirmed by this reaction? 26. (a) For the reaction $$2 \mathrm{~N}_2 \mathrm{O}_{5(\mathrm{~g})} \rightarrow 4 \mathrm{NO}_{2(\mathrm{~g})}+\mathrm{O} 27. (a) On the basic of crystal field theory write the electronic configuration for $$\mathrm{d}^5$$ ion with a strong field 28. (a) Illustrate Sandmeyer's reaction with an equation. (b) Explain, why $$\left(\mathrm{CH}_3\right)_2 \mathrm{NH}$$ is m 29. Give reasons for any 3 of the following observations: (a) Penta-acetate of glucose does not react with hydroxylamine. (b 30. (a) (i) Why is the $$\mathrm{C}-\mathrm{O}$$ bond length in phenols less than that in methanol? (ii) Arrange the followi 31. Read the passage carefully and answer the questions that follow : Nucleophilic Substitution Nucleophilic Substitution re 32. Rahul set-up an experiment to find resistance of aqueous $$\mathrm{KCl}$$ solution for different concentrations at $$298 33. (a) (i) Why is boiling point of $$1 \mathrm{~M} \mathrm{~NaCl}$$ solution more than that of $$1 \mathrm{M}$$ glucose sol 34. (a) (i) Write the reaction involved in Cannizaro's reaction. (ii) Why are the boiling point of aldehydes and ketones low 35. (a) Why is chemistry of actinoids complicated as compared to lanthanoids? (b) Complete the following reaction and justif

CBSE 12th Chemistry Delhi Set 1 - 2023

Subjective

-0

(a) Why is chemistry of actinoids complicated as compared to lanthanoids?

(b) Complete the following reaction and justify that it is a disproportionation reaction:

$$3 \mathrm{MnO}_4^{2-}+4 \mathrm{H}^{+} \rightarrow$$________ $$+$$ _________ $$+$$ $$\mathrm{H}_2 \mathrm{O}$$.

CBSE 12th Chemistry Delhi Set 1 - 2023 Chemistry - d and f Block Elements Question 2 English

Explain the reason why $$\mathrm{Cr}$$ has highest melting point and manganese $$(\mathrm{Mn})$$ a lower melting point.

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