CBSE Class 12 Chemistry 2022 question paper (56/5)

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 $\mathrm{Lmol^{-1}s^{-1}}$
Q.22 marks $Arrange the following in the increasing order of their property indicated : (a) Ethanal, Propanone, Propanal, Butanone (reactivity towards nucleophilic addition) (b) 4-Nitrobenzoic acid, benzoic acid, 3,4-Dinitrobenzoic acid, 4-Methoxy benzoic acid (Acid strength)$
Q.32 marks $Explain the following reactions : (a) Wolff Kishner reduction (b) Cannizzaro reaction$

Section B

3 marks each

Q.43 marks $k$
Q.5 (a)3 marks $\mathrm{K_2[PdCl_4]}$
OR
Q.5 (b)3 marks $(i) Why chelate complexes are more stable than complexes with unidentate ligands ? (ii) What is "spectrochemical series" ? What is the difference between a weak field ligand and a strong field ligand ?$
Q.6 (a)3 marks $(i) Define coagulation. (ii) State Hardy-Schulze rule. (iii) What is Electrophoresis?$
OR
Q.6 (b)3 marks $Write three differences between Physisorption and Chemisorption.$
Q.73 marks $(a) Write any two consequences of Lanthanoid Contraction. (b) Name the element of 3d series which exhibits the largest number of oxidation states. Give reason.$
Q.83 marks $Give reasons for the following statements : (a) Copper does not displace hydrogen from acids. (b) Transition metals and most of their compounds show paramagnetic behaviour. (c) Zn, Cd and Hg are soft metals.$
Q.9 (a)3 marks $\mathrm{pk_b}$
OR
Q.9 (b)3 marks $\mathrm{CH_3NH_2}$
Q.103 marks $\mathrm{C_6H_7N}$
Q.11 (a)3 marks $\mathrm{CH_3CN}$
OR
Q.11 (b)3 marks $Convert the following : (i) Benzoic acid to Benzaldehyde (ii) Propan-1-ol to 2-Bromopropanoic acid (iii) Acetaldehyde to But-2-enal$

Section C

Oxidation-reduction reactions are commonly known as redox reactions. They involve transfer of electrons from one species to another. In a spontaneous reaction, energy is released which can be used to do useful work. The reaction is split into two half reactions. Two different containers are used and a wire is used to drive the electrons from one side to the other and a Voltaic/Galvanic cell is created. It is an electrochemical cell that uses spontaneous redox reactions to generate electricity. A salt bridge also connects to the half cells. The reading of the voltmeter gives the cell voltage or cell potential or electromotive force. If $\mathrm{E^{o}_{cell}}$ is positive the reaction is spontaneous and if it is negative the reaction is non-spontaneous and is referred to as electrolytic cell. Electrolysis refers to the decomposition of a substance by an electric current. One mole of electric charge when passed through a cell will discharge half a mole of a divalent metal ion such as $\mathrm{Cu^{2+}}$ . This was first formulated by Faraday in the form of laws of electrolysis. The conductance of material is the property of materials due to which a material allows the flow of ions through itself and thus conducts electricity. Conductivity is represented by k and it depends upon nature and concentration of electrolyte, temperature etc. A more common term molar conductivity of a solution at a given concentration is conductance of the volume of solution containing one mole of electrolyte kept between two electrodes with the unit area of cross-section and distance of unit length. Limiting molar conductivity of weak electrolytes cannot be obtained graphically.
Q.12 (a)1 mark $Is silver plate the anode or cathode?$
Q.12 (b)1 mark $What will happen if the salt bridge is removed?$
Q.12 (c)1 mark $When does electrochemical cell behaves like an electrolytic cell?$
Q.12 (d)2 marks $\mathrm{Zn^{2+}}$
OR
Q.12 (d)2 marks $\mathrm{cm^2\,mol^{-1}}$

Section A

2 marks each

Q.12 marks $Arrange the following in the increasing order of their property indicated : (a) Ethanal, Propanone, Propanal, Butanone (reactivity towards nucleophilic addition) (b) 4-Nitrobenzoic acid, benzoic acid, 3,4-Dinitrobenzoic acid, 4-Methoxy benzoic acid (Acid strength)$
Q.22 marks $Explain the following reactions : (a) Clemmensen reduction (b) Stephen reaction$
Q.32 marks $\mathrm{Lmol^{-1}s^{-1}}$

Section B

3 marks each

Q.4 (a)3 marks $(i) Define coagulation. (ii) State Hardy-Schulze rule. (iii) What is Electrophoresis?$
OR
Q.4 (b)3 marks $Write three differences between Physisorption and Chemisorption.$
Q.5 (a)3 marks $\mathrm{[Pt(NH_3)_6]Cl_4}$
OR
Q.5 (b)3 marks $(i) Using IUPAC norms write the formulas for the following : (i.i) Pentaamminenitrito-N-Cobalt (III) (i.ii) Tetrahydroxidozincate (II) (ii) What is crystal field splitting energy ?$
Q.63 marks $(a) Write any two consequences of Lanthanoid Contraction. (b) Name the element of 3d series which exhibits the largest number of oxidation states. Give reason.$
Q.73 marks $k$
Q.83 marks $\mathrm{[Ti(H_2O)]^{3+}}$
Q.9 (a)3 marks $\mathrm{CH_3CN}$
OR
Q.9 (b)3 marks $Convert the following : (i) Benzoic acid to Benzaldehyde (ii) Propan-1-ol to 2-Bromopropanoic acid (iii) Acetaldehyde to But-2-enal$
Q.103 marks $\mathrm{C_2H_7N}$
Q.11 (a)3 marks $\mathrm{pk_b}$
OR
Q.11 (b)3 marks $\mathrm{CH_3NH_2}$

Section C

Oxidation-reduction reactions are commonly known as redox reactions. They involve transfer of electrons from one species to another. In a spontaneous reaction, energy is released which can be used to do useful work. The reaction is split into two half reactions. Two different containers are used and a wire is used to drive the electrons from one side to the other and a Voltaic/Galvanic cell is created. It is an electrochemical cell that uses spontaneous redox reactions to generate electricity. A salt bridge also connects to the half cells. The reading of the voltmeter gives the cell voltage or cell potential or electromotive force. If $\mathrm{E^{o}_{cell}}$ is positive the reaction is spontaneous and if it is negative the reaction is non-spontaneous and is referred to as electrolytic cell. Electrolysis refers to the decomposition of a substance by an electric current. One mole of electric charge when passed through a cell will discharge half a mole of a divalent metal ion such as $\mathrm{Cu^{2+}}$ . This was first formulated by Faraday in the form of laws of electrolysis. The conductance of material is the property of materials due to which a material allows the flow of ions through itself and thus conducts electricity. Conductivity is represented by k and it depends upon nature and concentration of electrolyte, temperature etc. A more common term molar conductivity of a solution at a given concentration is conductance of the volume of solution containing one mole of electrolyte kept between two electrodes with the unit area of cross-section and distance of unit length. Limiting molar conductivity of weak electrolytes cannot be obtained graphically.
Q.12 (a)1 mark $Is silver plate the anode or cathode?$
Q.12 (b)1 mark $What will happen if the salt bridge is removed?$
Q.12 (c)1 mark $When does electrochemical cell behaves like an electrolytic cell?$
Q.12 (d)2 marks $\mathrm{Zn^{2+}}$
OR
Q.12 (d)2 marks $\mathrm{cm^2\,mol^{-1}}$

Section A

2 marks each

Q.12 marks $Explain the following reactions : (a) Wolff Kishner reduction (b) Cannizzaro reaction$
Q.22 marks $\mathrm{CH_3COOH}$
Q.32 marks $\mathrm{Lmol^{-1}s^{-1}}$

Section B

3 marks each

Q.4 (a)3 marks $\mathrm{pk_b}$
OR
Q.4 (b)3 marks $\mathrm{CH_3NH_2}$
Q.53 marks $\mathrm{K_3[Cr(C_2O_4)_3]}$
Q.63 marks $(a) Write any two consequences of Lanthanoid Contraction. (b) Name the element of 3d series which exhibits the largest number of oxidation states. Give reason.$
Q.73 marks $k$
Q.83 marks $\mathrm{E^{o}_{(Mn^{2+}/Mn)}}$
Q.9 (a)3 marks $(i) Define coagulation. (ii) State Hardy-Schulze rule. (iii) What is Electrophoresis?$
OR
Q.9 (b)3 marks $Write three differences between Physisorption and Chemisorption.$
Q.10 (a)3 marks $\mathrm{C_7H_6O_2}$
OR
Q.10 (b)3 marks $\mathrm{C_6H_7N}$
Q.11 (a)3 marks $\mathrm{CH_3CN}$
OR
Q.11 (b)3 marks $Convert the following : (i) Benzoic acid to Benzaldehyde (ii) Propan-1-ol to 2-Bromopropanoic acid (iii) Acetaldehyde to But-2-enal$

Section C

Oxidation-reduction reactions are commonly known as redox reactions. They involve transfer of electrons from one species to another. In a spontaneous reaction, energy is released which can be used to do useful work. The reaction is split into two half reactions. Two different containers are used and a wire is used to drive the electrons from one side to the other and a Voltaic/Galvanic cell is created. It is an electrochemical cell that uses spontaneous redox reactions to generate electricity. A salt bridge also connects to the half cells. The reading of the voltmeter gives the cell voltage or cell potential or electromotive force. If $\mathrm{E^{o}_{cell}}$ is positive the reaction is spontaneous and if it is negative the reaction is non-spontaneous and is referred to as electrolytic cell. Electrolysis refers to the decomposition of a substance by an electric current. One mole of electric charge when passed through a cell will discharge half a mole of a divalent metal ion such as $\mathrm{Cu^{2+}}$ . This was first formulated by Faraday in the form of laws of electrolysis. The conductance of material is the property of materials due to which a material allows the flow of ions through itself and thus conducts electricity. Conductivity is represented by k and it depends upon nature and concentration of electrolyte, temperature etc. A more common term molar conductivity of a solution at a given concentration is conductance of the volume of solution containing one mole of electrolyte kept between two electrodes with the unit area of cross-section and distance of unit length. Limiting molar conductivity of weak electrolytes cannot be obtained graphically.
Q.12 (a)1 mark $Is silver plate the anode or cathode?$
Q.12 (b)1 mark $What will happen if the salt bridge is removed?$
Q.12 (c)1 mark $When does electrochemical cell behaves like an electrolytic cell?$
Q.12 (d)2 marks $\mathrm{Zn^{2+}}$
OR
Q.12 (d)2 marks $\mathrm{cm^2\,mol^{-1}}$