CBSE Class 12 Chemistry 2022 question paper (56/3)
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 marksPredict the reagent for carrying out the following transformations : (Any two) (i) Benzoyl chloride to Benzaldehyde (ii) Ethanal to 3-hydroxy butanal (iii) Ethanoic acid to 2-chloroethanoic acid
- Q.22 marks(i) Why on dilution the of increases very fast, while that of increases gradually ? (ii) What happens if external potential applied becomes greater than cell of electrochemical cell ?
- Q.32 marksAn Organic compound (A) with molecular formula on heating with and KOH forms a compound (B). Compound (B) on heating with and alcoholic KOH produces a foul smelling compound (C) and on reacting with forms a compound (D) which is soluble in alkali. Write the structures of (A), (B), (C) and (D).
Section B
3 marks each
- Q.43 marksAccount for the following : (i) salts are coloured while salts are white. (ii) value for the couple is much more positive than that for . (iii) Transition metals form alloys.
- Q.5 (a)3 marksCalculate and log Kc for the following cell : Given that cell = 1.05V, IF = 96,500 .
OR
Q.5 (b)3 marksCalculate the e.m.f. of the following cell at 298K : Given that cell = +0.44 V [log 2 = 0.3010 log 3 = 0.4771 log 10 = 1]- Q.63 marks(a) Using valence bond theory, predict the hybridization and magnetic character of following : [Atomic number of Co = 27] (b) Write IUPAC name of the following complex : (c) How many ions are produced from the complex in solution ?
- Q.7 (a)3 marksDifferentiate between the following : (i) Adsorption and Absorption (ii) Lyophobic Sol and Lyophilic Sol (iii) Multimolecular Colloid and Macromolecular colloid.
OR
Q.7 (b)3 marks(I) Define the following terms : (i) Zeta Potential (ii) Coagulation (II) Why a negatively charged sol is obtained when solution is added to KI solution ?- Q.83 marksDefine transition metals. Why Zn, Cd and Hg are not called transition metals ? How is the variability in oxidation states of transition metals different from that of p-block elements ?
- Q.9 (a)3 marksWhat happens when (i) Propanone is treated with and then hydrolysed ? (ii) Ethanal is treated with excess ethanol and acid ? (iii) Methanal undergoes Cannizzaro reaction ?
OR
Q.9 (b)3 marksWrite the main product in the following reactions : (i) (ii) (iii)- Q.103 marksGive reasons : (i) Ammonolysis of alkyl halides is not a good method to prepare pure primary amines. (ii) Aniline does not give Friedel-Crafts reaction. (iii) Although group is o/p directing in electrophilic substitution reactions, yet aniline on nitration gives good yield of m-nitroaniline.
- Q.11 (a)3 marks(i) Which acid of the following pair would you expect to be stronger ? or (ii) Arrange the following compounds in increasing order of their boiling points : (iii) Give simple chemical test to distinguish between Benzaldehyde and Acetophenone.
OR
Q.11 (b)3 marks(i) Which will undergo faster nucleophilic addition reaction ? Acetaldehyde or Propanone (ii) What is the composition of Fehling's reagent ? (iii) Draw structure of the semicarbazone of Ethanal.
Section C
- The rate of reaction is concerned with decrease in concentration of reactants or increase in the concentration of products per unit time. It can be expressed as instantaneous rate at a particular instant of time and average rate over a large interval of time. A number of factors such as temperature, concentration of reactants, catalyst affect the rate of reaction. Mathematical representation of rate of a reaction is given by rate law : x and y indicate how sensitive the rate is to the change in concentration of A and B. Sum of x + y gives the overall order of a reaction. When a sequence of elementary reactions gives us the products, the reactions are called complex reactions. Molecularity and order of an elementary reaction are same. Zero order reactions are relatively uncommon but they occur under special conditions. All natural and artificial radioactive decay of unstable nuclei take place by first order kinetics.Q.12 (a)1 markWhat is the effect of temperature on the rate constant of a reaction ?
- Q.12 (b)1 markFor a reaction A + B Product, the rate law is given by, Rate = . What is the order of the reaction ?
- Q.12 (c)1 markHow order and molecularity are different for complex reactions ?
- Q.12 (d)2 marksA first order reaction has a rate constant . How long will 6g of this reactant take to reduce to 2g ?
OR
Q.12 (d) OR2 marksThe half life for radioactive decay of is 6930 years. An archaeological artifact containing wood had only 75% of the found in a living tree. Find the age of the sample. [log 4 = 0.6021 log 3 = 0.4771 log 2 = 0.3010 log 10 = 1]
Section A
2 marks each
- Q.12 marksArrange the following compounds in increasing order of their property as indicated in bracket : (Any two) (i) (reactivity towards HCN) (ii) (acid strength) (iii) 2,4-Dinitrobenzoic acid, 4-Nitrobenzoic acid, 4-Methoxybenzoic acid, Benzoic acid (acid strength)
- Q.22 marksAn Organic compound (A) with molecular formula on heating with and KOH forms a compound (B). Compound (B) on heating with and alcoholic KOH produces a foul smelling compound (C) and on reacting with forms a compound (D) which is soluble in alkali. Write the structures of (A), (B), (C) and (D).
- Q.32 marksDefine conductivity for the solution of an electrolyte. Why does the conductivity of a solution decrease with dilution ?
Section B
3 marks each
- Q.43 marksAccount for the following : (i) is a strong reducing agent. (ii) is coloured whereas is colourless in aqueous solution. (iii) Zn, Cd and Hg are not called transition elements.
- Q.5 (a)3 marksDifferentiate between the following : (i) Adsorption and Absorption (ii) Lyophobic Sol and Lyophilic Sol (iii) Multimolecular Colloid and Macromolecular colloid.
OR
Q.5 (b)3 marks(I) Define the following terms : (i) Zeta Potential (ii) Coagulation (II) Why a negatively charged sol is obtained when solution is added to KI solution ?- Q.6 (a)3 marksWhat happens when (i) Propanone is treated with and then hydrolysed ? (ii) Ethanal is treated with excess ethanol and acid ? (iii) Methanal undergoes Cannizzaro reaction ?
OR
Q.6 (b)3 marksWrite the main product in the following reactions : (i) (ii) (iii)- Q.73 marksWhat is Lanthanoid contraction ? What is the cause of Lanthanoid contraction ? Write two consequences of Lanthanoid contraction.
- Q.8 (a)3 marks(i) Which acid of the following pair would you expect to be stronger ? or (ii) Arrange the following compounds in increasing order of their boiling points : (iii) Give simple chemical test to distinguish between Benzaldehyde and Acetophenone.
OR
Q.8 (b)3 marks(i) Which will undergo faster nucleophilic addition reaction ? Acetaldehyde or Propanone (ii) What is the composition of Fehling's reagent ? (iii) Draw structure of the semicarbazone of Ethanal.- Q.93 marksGive reasons : (i) Ammonolysis of alkyl halides is not a good method to prepare pure primary amines. (ii) Aniline does not give Friedel-Crafts reaction. (iii) Although group is o/p directing in electrophilic substitution reactions, yet aniline on nitration gives good yield of m-nitroaniline.
- Q.103 marks(a) Using valence bond theory, predict the hybridization and magnetic character of following : [Atomic number of Co = 27] (b) Write IUPAC name of the following complex : (c) How many ions are produced from the complex in solution ?
- Q.11 (a)3 marksCalculate and log Kc for the following cell : Given that cell = 1.05V, IF = 96,500 .
OR
Q.11 (b)3 marksCalculate the e.m.f. of the following cell at 298K : Given that cell = +0.44 V [log 2 = 0.3010 log 3 = 0.4771 log 10 = 1]
Section C
- The rate of reaction is concerned with decrease in concentration of reactants or increase in the concentration of products per unit time. It can be expressed as instantaneous rate at a particular instant of time and average rate over a large interval of time. A number of factors such as temperature, concentration of reactants, catalyst affect the rate of reaction. Mathematical representation of rate of a reaction is given by rate law : x and y indicate how sensitive the rate is to the change in concentration of A and B. Sum of x + y gives the overall order of a reaction. When a sequence of elementary reactions gives us the products, the reactions are called complex reactions. Molecularity and order of an elementary reaction are same. Zero order reactions are relatively uncommon but they occur under special conditions. All natural and artificial radioactive decay of unstable nuclei take place by first order kinetics.Q.12 (a)1 markWhat is the effect of temperature on the rate constant of a reaction ?
- Q.12 (b)1 markFor a reaction A + B Product, the rate law is given by, Rate = . What is the order of the reaction ?
- Q.12 (c)1 markHow order and molecularity are different for complex reactions ?
- Q.12 (d)2 marksA first order reaction has a rate constant . How long will 6g of this reactant take to reduce to 2g ?
OR
Q.12 (d) OR2 marksThe half life for radioactive decay of is 6930 years. An archaeological artifact containing wood had only 75% of the found in a living tree. Find the age of the sample. [log 4 = 0.6021 log 3 = 0.4771 log 2 = 0.3010 log 10 = 1]
Section A
2 marks each
- Q.12 marksAn Organic compound (A) with molecular formula on heating with and KOH forms a compound (B). Compound (B) on heating with and alcoholic KOH produces a foul smelling compound (C) and on reacting with forms a compound (D) which is soluble in alkali. Write the structures of (A), (B), (C) and (D).
- Q.22 marksWrite the products formed when benzaldehyde reacts with the following reagents (Any two) : (i) in presence of dilute NaOH (ii) in presence of weak acid (iii) Tollen's reagent
- Q.32 marksThe conductivity of 0.001M acetic acid is . Calculate its degree of dissociation if for acetic acid is .
Section B
3 marks each
- Q.43 marks(i) Why are melting points of transition metals high ? (ii) Why the transition metals generally form coloured compounds ? (iii) Why value for couple is highly positive ?
- Q.5 (a)3 marks(i) Which acid of the following pair would you expect to be stronger ? or (ii) Arrange the following compounds in increasing order of their boiling points : (iii) Give simple chemical test to distinguish between Benzaldehyde and Acetophenone.
OR
Q.5 (b)3 marks(i) Which will undergo faster nucleophilic addition reaction ? Acetaldehyde or Propanone (ii) What is the composition of Fehling's reagent ? (iii) Draw structure of the semicarbazone of Ethanal.- Q.63 marksGive reasons : (i) Ammonolysis of alkyl halides is not a good method to prepare pure primary amines. (ii) Aniline does not give Friedel-Crafts reaction. (iii) Although group is o/p directing in electrophilic substitution reactions, yet aniline on nitration gives good yield of m-nitroaniline.
- Q.7 (a)3 marksWhat happens when (i) Propanone is treated with and then hydrolysed ? (ii) Ethanal is treated with excess ethanol and acid ? (iii) Methanal undergoes Cannizzaro reaction ?
OR
Q.7 (b)3 marksWrite the main product in the following reactions : (i) (ii) (iii)- Q.8 (a)3 marksDifferentiate between the following : (i) Adsorption and Absorption (ii) Lyophobic Sol and Lyophilic Sol (iii) Multimolecular Colloid and Macromolecular colloid.
OR
Q.8 (b)3 marks(I) Define the following terms : (i) Zeta Potential (ii) Coagulation (II) Why a negatively charged sol is obtained when solution is added to KI solution ?- Q.93 marksDefine transition metals. Why Zn, Cd and Hg are not called transition metals ? How is the variability in oxidation states of transition metals different from that of p-block elements ?
- Q.103 marks(a) Using valence bond theory, predict the hybridization and magnetic character of the complex : (Atomic number : Ni = 28) (b) Write IUPAC name of . (c) Why is a more stable complex than ?
- Q.11 (a)3 marksCalculate and log Kc for the following cell : Given that cell = 1.05V, IF = 96,500 .
OR
Q.11 (b)3 marksCalculate the e.m.f. of the following cell at 298K : Given that cell = +0.44 V [log 2 = 0.3010 log 3 = 0.4771 log 10 = 1]
Section C
- The rate of reaction is concerned with decrease in concentration of reactants or increase in the concentration of products per unit time. It can be expressed as instantaneous rate at a particular instant of time and average rate over a large interval of time. A number of factors such as temperature, concentration of reactants, catalyst affect the rate of reaction. Mathematical representation of rate of a reaction is given by rate law : x and y indicate how sensitive the rate is to the change in concentration of A and B. Sum of x + y gives the overall order of a reaction. When a sequence of elementary reactions gives us the products, the reactions are called complex reactions. Molecularity and order of an elementary reaction are same. Zero order reactions are relatively uncommon but they occur under special conditions. All natural and artificial radioactive decay of unstable nuclei take place by first order kinetics.Q.12 (a)1 markWhat is the effect of temperature on the rate constant of a reaction ?
- Q.12 (b)1 markFor a reaction A + B Product, the rate law is given by, Rate = . What is the order of the reaction ?
- Q.12 (c)1 markHow order and molecularity are different for complex reactions ?
- Q.12 (d)2 marksA first order reaction has a rate constant . How long will 6g of this reactant take to reduce to 2g ?
OR
Q.12 (d) OR2 marksThe half life for radioactive decay of is 6930 years. An archaeological artifact containing wood had only 75% of the found in a living tree. Find the age of the sample. [log 4 = 0.6021 log 3 = 0.4771 log 2 = 0.3010 log 10 = 1]