CBSE Class 12 Chemistry 2022 question paper (56/1)

Maximum marks 35 · Time 2 hours · 3 sets

Try each question first, then open its model answer. Where the paper offers a choice, both questions are shown with OR between them.

Section A

2 marks each

Q.12 marks $Define rate of reaction. Write two factors that affect the rate of reaction.$
Q.22 marks $\mathrm{C_2H_5NH_2}$
Q.32 marks $\mathrm{Zn(s)} + \mathrm{Cu^{2+}\,(aq)} \rightarrow \mathrm{Zn^{2+}\,(aq)} + \mathrm{Cu(s)}$

Section B

3 marks each

Q.43 marks $\mathrm{Ti^{4+}}$
Q.5 (a)3 marks $\mathrm{d^4}$
OR
Q.5 (b)3 marks $\mathrm{NiCl_2 \cdot 6H_2O}$
Q.63 marks $A first order reaction is 50% complete in 40 minutes. Calculate the time required for the completion of 90% of reaction. [Given : log 2 = 0.3010, log 10 = 1]$
Q.7 (a)3 marks $Illustrate the following reactions giving suitable example in each case : (i) Gabriel phthalimide synthesis. (ii) Carbylamine reaction. (iii) Hoffmann bromamide degradation reaction.$
OR
Q.7 (b)3 marks $\mathrm{CH_3CH_2Cl} \xrightarrow{\mathrm{KCN}} \mathrm{A} \xrightarrow{\mathrm{LiAlH_4}} \mathrm{B} \xrightarrow[0\,^\circ\mathrm{C}]{\mathrm{HNO_2}} \mathrm{C}$
Q.8 (a)3 marks $\mathrm{E^{o}_{M^{2+}/M}}$
OR
Q.8 (b)3 marks $Define transition elements. Which of the d-block elements may not be regarded as the transition elements ? Why transition metals generally form coloured compounds ?$
Q.93 marks $\mathrm{C_5H_{10}O}$
Q.10 (a)3 marks $Write any three differences between physisorption and chemisorption.$
OR
Q.10 (b)3 marks $Define the following terms with a suitable example in each : (i) Lyophilic sol (ii) Macromolecular colloid (iii) Coagulation$
Q.113 marks $(\Delta_{\mathrm{r}}\mathrm{G}^{\circ})$

Section C

Aldehydes, ketones and carboxylic acids are some of the important classes of organic compounds containing carbonyl group. These are highly polar molecules due to higher electro-negativity of oxygen relative to carbon in the carbonyl group. Aldehydes are prepared by dehydrogenation or controlled oxidation of primary alcohols and controlled reduction of acyl halides. Ketones are prepared by oxidation of secondary alcohols and hydration of alkynes. Aldehydes and ketones undergo nucleophilic addition reactions onto the carbonyl group but carboxylic acid does not undergo nucleophilic addition reaction. The alpha $(\alpha)$ – hydrogens of aldehydes and ketones are acidic. Therefore aldehydes and ketones having at least one $\alpha$ -hydrogen undergo Aldol condensation. Aldehydes are easily oxidised by mild oxidising agents such as Tollens' reagent and Fehling's reagent. Carboxylic acids are prepared by the oxidation of primary alcohols, aldehydes and by hydrolysis of nitriles. Aromatic carboxylic acids are prepared by side-chain oxidation of alkyl benzenes. Carboxylic acids are considerably more acidic than alcohols and most of simple phenols.
Q.12 (a)1 mark $\mathrm{CH_3COCH_3}$
Q.12 (b)1 mark $Give a simple chemical test to distinguish between Ethanal and Propanone.$
Q.12 (c)1 mark $Why carboxylic acid does not give nucleophilic addition reactions like aldehydes and ketones ?$
Q.12 (d)2 marks $\alpha$
OR
Q.12 (d) OR2 marks $\mathrm{C_6H_5CH_2-CH_3} \xrightarrow[\mathrm{(b)\ H^{+}}]{\mathrm{(a)\ KMnO_4,\ KOH}}$

Section A

2 marks each

Q.12 marks $(a) A reaction is second order in X and first order in Y. How is the rate affected when the concentrations of both X and Y are doubled ? (b) Write the units of 'k' for (i) zero order reaction (ii) first order reaction$
Q.22 marks $\mathrm{CH_3COOH}$
Q.32 marks $\mathrm{C_2H_5NH_2}$

Section B

3 marks each

Q.4 (a)3 marks $\mathrm{d^4}$
OR
Q.4 (b)3 marks $\mathrm{NiCl_2 \cdot 6H_2O}$
Q.53 marks $A first order reaction is 50% complete in 40 minutes. Calculate the time required for the completion of 90% of reaction. [Given : log 2 = 0.3010, log 10 = 1]$
Q.6 (a)3 marks $Illustrate the following reactions giving suitable example in each case : (i) Gabriel phthalimide synthesis. (ii) Carbylamine reaction. (iii) Hoffmann bromamide degradation reaction.$
OR
Q.6 (b)3 marks $\mathrm{CH_3CH_2Cl} \xrightarrow{\mathrm{KCN}} \mathrm{A} \xrightarrow{\mathrm{LiAlH_4}} \mathrm{B} \xrightarrow[0\,^\circ\mathrm{C}]{\mathrm{HNO_2}} \mathrm{C}$
Q.7 (a)3 marks $Write any three differences between physisorption and chemisorption.$
OR
Q.7 (b)3 marks $Define the following terms with a suitable example in each : (i) Lyophilic sol (ii) Macromolecular colloid (iii) Coagulation$
Q.83 marks $\mathrm{V^{3+}}$
Q.93 marks $(\Delta_{\mathrm{r}}\mathrm{G}^{\circ})$
Q.103 marks $\mathrm{C_5H_{10}O}$
Q.11 (a)3 marks $\mathrm{Eu^{2+}}$
OR
Q.11 (b)3 marks $What is Lanthanoid contraction ? Write two consequences of Lanthanoid contraction.$

Section C

Aldehydes, ketones and carboxylic acids are some of the important classes of organic compounds containing carbonyl group. These are highly polar molecules due to higher electro-negativity of oxygen relative to carbon in the carbonyl group. Aldehydes are prepared by dehydrogenation or controlled oxidation of primary alcohols and controlled reduction of acyl halides. Ketones are prepared by oxidation of secondary alcohols and hydration of alkynes. Aldehydes and ketones undergo nucleophilic addition reactions onto the carbonyl group but carboxylic acid does not undergo nucleophilic addition reaction. The alpha $(\alpha)$ – hydrogens of aldehydes and ketones are acidic. Therefore aldehydes and ketones having at least one $\alpha$ -hydrogen undergo Aldol condensation. Aldehydes are easily oxidised by mild oxidising agents such as Tollens' reagent and Fehling's reagent. Carboxylic acids are prepared by the oxidation of primary alcohols, aldehydes and by hydrolysis of nitriles. Aromatic carboxylic acids are prepared by side-chain oxidation of alkyl benzenes. Carboxylic acids are considerably more acidic than alcohols and most of simple phenols.
Q.12 (a)1 mark $\mathrm{CH_3COCH_3}$
Q.12 (b)1 mark $Give a simple chemical test to distinguish between Ethanal and Propanone.$
Q.12 (c)1 mark $Why carboxylic acid does not give nucleophilic addition reactions like aldehydes and ketones ?$
Q.12 (d)2 marks $\alpha$
OR
Q.12 (d) OR2 marks $\mathrm{C_6H_5CH_2-CH_3} \xrightarrow[\mathrm{(b)\ H^{+}}]{\mathrm{(a)\ KMnO_4,\ KOH}}$

Section A

2 marks each

Q.12 marks $\mathrm{C_2H_5NH_2}$
Q.22 marks $\Lambda_{\mathrm{m}}$
Q.32 marks $What do you mean by complex reactions ? Can we determine order and molecularity of a complex reaction ?$

Section B

3 marks each

Q.4 (a)3 marks $Write any three differences between physisorption and chemisorption.$
OR
Q.4 (b)3 marks $Define the following terms with a suitable example in each : (i) Lyophilic sol (ii) Macromolecular colloid (iii) Coagulation$
Q.5 (a)3 marks $Illustrate the following reactions giving suitable example in each case : (i) Gabriel phthalimide synthesis. (ii) Carbylamine reaction. (iii) Hoffmann bromamide degradation reaction.$
OR
Q.5 (b)3 marks $\mathrm{CH_3CH_2Cl} \xrightarrow{\mathrm{KCN}} \mathrm{A} \xrightarrow{\mathrm{LiAlH_4}} \mathrm{B} \xrightarrow[0\,^\circ\mathrm{C}]{\mathrm{HNO_2}} \mathrm{C}$
Q.63 marks $\mathrm{C_5H_{10}O}$
Q.7 (a)3 marks $\mathrm{d^4}$
OR
Q.7 (b)3 marks $\mathrm{NiCl_2 \cdot 6H_2O}$
Q.8 (a)3 marks $Account for the following : (i) Zr and Hf have almost similar atomic radii. (ii) Transition metals show variable oxidation states. (iii) Zinc has lowest enthalpy of atomisation.$
OR
Q.8 (b)3 marks $Why transition metals and their compounds act as good catalyst ? How is the variability in oxidation states of transition metals different from that of the non-transition metals ? Illustrate with examples.$
Q.93 marks $(\Delta_{\mathrm{r}}\mathrm{G}^{\circ})$
Q.103 marks $\mathrm{Ti^{2+}}$
Q.113 marks $A first order reaction is 50% complete in 40 minutes. Calculate the time required for the completion of 90% of reaction. [Given : log 2 = 0.3010, log 10 = 1]$

Section C

Aldehydes, ketones and carboxylic acids are some of the important classes of organic compounds containing carbonyl group. These are highly polar molecules due to higher electro-negativity of oxygen relative to carbon in the carbonyl group. Aldehydes are prepared by dehydrogenation or controlled oxidation of primary alcohols and controlled reduction of acyl halides. Ketones are prepared by oxidation of secondary alcohols and hydration of alkynes. Aldehydes and ketones undergo nucleophilic addition reactions onto the carbonyl group but carboxylic acid does not undergo nucleophilic addition reaction. The alpha $(\alpha)$ – hydrogens of aldehydes and ketones are acidic. Therefore aldehydes and ketones having at least one $\alpha$ -hydrogen undergo Aldol condensation. Aldehydes are easily oxidised by mild oxidising agents such as Tollens' reagent and Fehling's reagent. Carboxylic acids are prepared by the oxidation of primary alcohols, aldehydes and by hydrolysis of nitriles. Aromatic carboxylic acids are prepared by side-chain oxidation of alkyl benzenes. Carboxylic acids are considerably more acidic than alcohols and most of simple phenols.
Q.12 (a)1 mark $\mathrm{CH_3COCH_3}$
Q.12 (b)1 mark $Give a simple chemical test to distinguish between Ethanal and Propanone.$
Q.12 (c)1 mark $Why carboxylic acid does not give nucleophilic addition reactions like aldehydes and ketones ?$
Q.12 (d)2 marks $\alpha$
OR
Q.12 (d) OR2 marks $\mathrm{C_6H_5CH_2-CH_3} \xrightarrow[\mathrm{(b)\ H^{+}}]{\mathrm{(a)\ KMnO_4,\ KOH}}$