CBSE Class 12 Chemistry 2022 question paper (56/4)
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 marksArrange the following compounds in the increasing order of their property indicated : (Any two) (i) Acetaldehyde, Benzaldehyde, Acetophenone, Acetone (Reactivity towards HCN) (ii) , , (Acidic strength) (iii) , , (Boiling point)
- Q.22 marksIn a plot of against the square root of concentration () for strong and weak electrolyte, the value of limiting molar conductivity of a weak electrolyte cannot be obtained graphically. Suggest a way to obtain this value. Also state the related law, if any.
- Q.32 marksWrite reasons for the following statements : (i) Benzoic acid does not undergo Friedel-Crafts reaction. (ii) Oxidation of aldehydes is easier than that of ketones.
Section B
3 marks each
- Q.4 (a)3 marksWrite reasons for the following : (i) Ethylamine is soluble in water whereas aniline is insoluble. (ii) Amino group is o- and p-directing in aromatic electrophilic substitution reactions, but aniline on nitration gives a substantial amount of m-nitroaniline. (iii) Amines behave as nucleophiles.
OR
Q.4 (b)3 marksHow will you carry out the following conversions : (i) Nitrobenzene to Aniline (ii) Ethanamide to Methanamine (iii) Ethanenitrile to Ethanamine- Q.5 (a)3 marks(i) Write the electronic configuration of on the basis of crystal field splitting theory if . (ii) is weakly paramagnetic whereas is diamagnetic. Give reason to support this statement. [Atomic no. : Fe = 26] (iii) Write the number of ions produced from the complex in solution.
OR
Q.5 (b)3 marks(i) Calculate the spin only magnetic moment of the complex . (Atomic no. of Co = 27) (ii) Write the IUPAC name of the given complex : (iii) Which out of the two complexes is more stable and why ? ,- Q.63 marks(i) Which ion amongst the following is colourless and why ? , , (Atomic number of Ti = 22, Cr = 24, V = 23) (ii) Why is much more resistant than towards oxidation ? (iii) Highest oxidation state of a metal is shown in its oxide or fluoride only. Justify the statement.
- Q.73 marksA compound 'A' () on oxidation gives 'B' (). 'A' undergoes Iodoform reaction to give yellow precipitate and reacts with HCN to form the compound 'C'. 'C' on hydrolysis gives 2-hydroxypropanoic acid. Identify the compounds 'A', 'B' and 'C'. Write down equations for the reactions involved.
- Q.83 marksObserve the given figure and answer the following questions : (i) Write the expression for adsorption of gases on solids in the form of an equation. (ii) What is the slope of the graph ? (iii) What does the intercept of the line represent ?
- Q.9 (a)3 marksWrite equations involved in the following reactions : (i) Ethanamine reacts with acetyl chloride. (ii) Aniline reacts with bromine water at room temperature. (iii) Aniline reacts with chloroform and ethanolic potassium hydroxide.
OR
Q.9 (b)3 marks(i) Write the IUPAC name for the following organic compound : (ii) Write the equations for the following : (I) Gabriel phthalimide synthesis (II) Hoffmann bromamide degradation- Q.103 marksWrite the Nernst equation and calculate emf of the following cell at 298 K : Given : (log 10 = 1)
- Q.11 (a)3 marks(i) Silver atom has completely filled d-orbitals in its ground state, it is still considered to be a transition element. Justify the statement. (ii) Why are values of Mn and Zn more negative than expected ? (iii) Why do transition metals form alloys ?
OR
Q.11 (b)3 marksAnswer the following questions on the basis of the figure given below : (i) Which element in 3d series has lowest enthalpy of atomisation ? (ii) Why do metals of the second and third series have greater enthalpies of atomisation ? (iii) Why are enthalpies of atomisation of transition metals quite high ?
Section C
- The rate law for a chemical reaction relates the reaction rate with the concentrations or partial pressures of the reactants. For a general reaction aA + bB C with no intermediate steps in its reaction mechanism, meaning that it is an elementary reaction, the rate law is given by , where [A] and [B] express the concentrations of A and B in moles per litre. Exponents x and y vary for each reaction and are determined experimentally. The value of k varies with conditions that affect reaction rate, such as temperature, pressure, surface area, etc. The sum of these exponents is known as overall reaction order. A zero order reaction has a constant rate that is independent of the concentration of the reactants. A first order reaction depends on the concentration of only one reactant. A reaction is said to be second order when the overall order is two. Once we have determined the order of the reaction, we can go back and plug in one set of our initial values and solve for k.Q.12 (i)1 markCalculate the overall order of a reaction which has the following rate expression :
- Q.12 (ii)1 markWhat is the effect of temperature on rate of reaction ?
- Q.12 (iii)1 markWhat is meant by rate of a reaction ?
- Q.12 (iv) (a)2 marksA first order reaction takes minutes for 50% completion. Calculate the time required for 30% completion of this reaction. (log 10 = 1, log 7 = )
OR
Q.12 (iv) (b)2 marksA first order reaction has a rate constant per sec. How long will 5 g of this reactant take to reduce to 3 g ? (log 3 = ; log 5 = )
Section A
2 marks each
- Q.12 marksIn a plot of against the square root of concentration () for strong and weak electrolyte, the value of limiting molar conductivity of a weak electrolyte cannot be obtained graphically. Suggest a way to obtain this value. Also state the related law, if any.
- Q.22 marksWrite reasons for the following statements : (i) Benzoic acid does not undergo Friedel-Crafts reaction. (ii) Oxidation of aldehydes is easier than that of ketones.
- Q.32 marksGive reasons for the following statements : (Any two) (i) Benzaldehyde is less reactive than propanal in nucleophilic addition reactions. (ii) Carboxylic acids do not give reactions of carbonyl group. (iii) 4-nitrobenzoic acid is a stronger acid than benzoic acid.
Section B
3 marks each
- Q.4 (a)3 marks(i) Silver atom has completely filled d-orbitals in its ground state, it is still considered to be a transition element. Justify the statement. (ii) Why are values of Mn and Zn more negative than expected ? (iii) Why do transition metals form alloys ?
OR
Q.4 (b)3 marksAnswer the following questions on the basis of the figure given below : (i) Which element in 3d series has lowest enthalpy of atomisation ? (ii) Why do metals of the second and third series have greater enthalpies of atomisation ? (iii) Why are enthalpies of atomisation of transition metals quite high ?- Q.5 (a)3 marks(i) Write the electronic configuration of on the basis of crystal field splitting theory, if . (ii) with square-planar structure is diamagnetic and with tetrahedral geometry is paramagnetic. Give reason to support the statement. [Atomic number : Ni = 28] (iii) Write the number of ions produced in the solution from the following complex :
OR
Q.5 (b)3 marks(i) Calculate the spin only magnetic moment of the complex . (Atomic number of Fe = 26) (ii) Write the IUPAC name of the given complex : (iii) Why is the complex more stable than ?- Q.6 (a)3 marksWrite equations involved in the following reactions : (i) Ethanamine reacts with acetyl chloride. (ii) Aniline reacts with bromine water at room temperature. (iii) Aniline reacts with chloroform and ethanolic potassium hydroxide.
OR
Q.6 (b)3 marks(i) Write the IUPAC name for the following organic compound : (ii) Write the equations for the following : (I) Gabriel phthalimide synthesis (II) Hoffmann bromamide degradation- Q.7 (a)3 marksWrite reasons for the following : (i) Ethylamine is soluble in water whereas aniline is insoluble. (ii) Amino group is o- and p-directing in aromatic electrophilic substitution reactions, but aniline on nitration gives a substantial amount of m-nitroaniline. (iii) Amines behave as nucleophiles.
OR
Q.7 (b)3 marksHow will you carry out the following conversions : (i) Nitrobenzene to Aniline (ii) Ethanamide to Methanamine (iii) Ethanenitrile to Ethanamine- Q.83 marksA compound 'A' () on oxidation gives 'B' (). 'A' undergoes Iodoform reaction to give yellow precipitate and reacts with HCN to form the compound 'C'. 'C' on hydrolysis gives 2-hydroxypropanoic acid. Identify the compounds 'A', 'B' and 'C'. Write down equations for the reactions involved.
- Q.93 marks(i) Which ion amongst the following is colourless and why ? , , (Atomic number of Ti = 22, Cr = 24, V = 23) (ii) Why is much more resistant than towards oxidation ? (iii) Highest oxidation state of a metal is shown in its oxide or fluoride only. Justify the statement.
- Q.103 marksWrite the Nernst equation and calculate the emf of the following cell at 298 K : Given : [log 10 = 1]
- Q.113 marksObserve the given figure and answer the following questions : (i) Write the expression for adsorption of gases on solids in the form of an equation. (ii) What is the slope of the graph ? (iii) What does the intercept of the line represent ?
Section C
- The rate law for a chemical reaction relates the reaction rate with the concentrations or partial pressures of the reactants. For a general reaction aA + bB C with no intermediate steps in its reaction mechanism, meaning that it is an elementary reaction, the rate law is given by , where [A] and [B] express the concentrations of A and B in moles per litre. Exponents x and y vary for each reaction and are determined experimentally. The value of k varies with conditions that affect reaction rate, such as temperature, pressure, surface area, etc. The sum of these exponents is known as overall reaction order. A zero order reaction has a constant rate that is independent of the concentration of the reactants. A first order reaction depends on the concentration of only one reactant. A reaction is said to be second order when the overall order is two. Once we have determined the order of the reaction, we can go back and plug in one set of our initial values and solve for k.Q.12 (i)1 markCalculate the overall order of a reaction which has the following rate expression :
- Q.12 (ii)1 markWhat is the effect of temperature on rate of reaction ?
- Q.12 (iii)1 markWhat is meant by rate of a reaction ?
- Q.12 (iv) (a)2 marksA first order reaction takes minutes for 50% completion. Calculate the time required for 30% completion of this reaction. (log 10 = 1, log 7 = )
OR
Q.12 (iv) (b)2 marksA first order reaction has a rate constant per sec. How long will 5 g of this reactant take to reduce to 3 g ? (log 3 = ; log 5 = )
Section A
2 marks each
- Q.12 marksWrite reasons for the following statements : (i) Benzoic acid does not undergo Friedel-Crafts reaction. (ii) Oxidation of aldehydes is easier than that of ketones.
- Q.22 marksObserve the given figure and answer the following questions : (Any two) (i) What is the charge on AgI colloidal particles ? (ii) What is the reason for the origin of the charge on AgI ? (iii) If KI is added to , what will be the charge on AgI colloidal particles ?
- Q.32 marks(i) does not undergo aldol condensation. Why ? (ii) Distinguish between Acetophenone and Benzophenone with the help of a chemical test.
Section B
3 marks each
- Q.43 marksObserve the given figure and answer the following questions : (i) Write the expression for adsorption of gases on solids in the form of an equation. (ii) What is the slope of the graph ? (iii) What does the intercept of the line represent ?
- Q.5 (a)3 marks(i) Write the electronic configuration of on the basis of crystal field splitting theory if . (ii) is an inner orbital complex whereas is an outer orbital complex. (Atomic number : Co = 27, Ni = 28) (iii) Write the number of ions produced from the complex in solution.
OR
Q.5 (b)3 marks(i) Calculate the spin only magnetic moment of the complex . (Atomic number of Fe = 26) (ii) Which out of the following two complexes is more stable and why ? , (iii) Write the IUPAC name of the given complex :- Q.6 (a)3 marksWrite equations involved in the following reactions : (i) Ethanamine reacts with acetyl chloride. (ii) Aniline reacts with bromine water at room temperature. (iii) Aniline reacts with chloroform and ethanolic potassium hydroxide.
OR
Q.6 (b)3 marks(i) Write the IUPAC name for the following organic compound : (ii) Write the equations for the following : (I) Gabriel phthalimide synthesis (II) Hoffmann bromamide degradation- Q.7 (a)3 marksWrite reasons for the following : (i) Ethylamine is soluble in water whereas aniline is insoluble. (ii) Amino group is o- and p-directing in aromatic electrophilic substitution reactions, but aniline on nitration gives a substantial amount of m-nitroaniline. (iii) Amines behave as nucleophiles.
OR
Q.7 (b)3 marksHow will you carry out the following conversions : (i) Nitrobenzene to Aniline (ii) Ethanamide to Methanamine (iii) Ethanenitrile to Ethanamine- Q.83 marksArrange the following compounds in the increasing order of their property indicated : (i) Acetaldehyde, Benzaldehyde, Acetophenone, Acetone (Reactivity towards HCN) (ii) , , (Acidic strength) (iii) , , (Boiling point)
- Q.93 marks(i) Which ion amongst the following is colourless and why ? , , (Atomic number of Ti = 22, Cr = 24, V = 23) (ii) Why is much more resistant than towards oxidation ? (iii) Highest oxidation state of a metal is shown in its oxide or fluoride only. Justify the statement.
- Q.103 marksWrite the Nernst equation and calculate the emf of the following cell at 298 K : Given : (log 10 = 1)
- Q.11 (a)3 marks(i) Silver atom has completely filled d-orbitals in its ground state, it is still considered to be a transition element. Justify the statement. (ii) Why are values of Mn and Zn more negative than expected ? (iii) Why do transition metals form alloys ?
OR
Q.11 (b)3 marksAnswer the following questions on the basis of the figure given below : (i) Which element in 3d series has lowest enthalpy of atomisation ? (ii) Why do metals of the second and third series have greater enthalpies of atomisation ? (iii) Why are enthalpies of atomisation of transition metals quite high ?
Section C
- The rate law for a chemical reaction relates the reaction rate with the concentrations or partial pressures of the reactants. For a general reaction aA + bB C with no intermediate steps in its reaction mechanism, meaning that it is an elementary reaction, the rate law is given by , where [A] and [B] express the concentrations of A and B in moles per litre. Exponents x and y vary for each reaction and are determined experimentally. The value of k varies with conditions that affect reaction rate, such as temperature, pressure, surface area, etc. The sum of these exponents is known as overall reaction order. A zero order reaction has a constant rate that is independent of the concentration of the reactants. A first order reaction depends on the concentration of only one reactant. A reaction is said to be second order when the overall order is two. Once we have determined the order of the reaction, we can go back and plug in one set of our initial values and solve for k.Q.12 (i)1 markCalculate the overall order of a reaction which has the following rate expression :
- Q.12 (ii)1 markWhat is the effect of temperature on rate of reaction ?
- Q.12 (iii)1 markWhat is meant by rate of a reaction ?
- Q.12 (iv) (a)2 marksA first order reaction takes minutes for 50% completion. Calculate the time required for 30% completion of this reaction. (log 10 = 1, log 7 = )
OR
Q.12 (iv) (b)2 marksA first order reaction has a rate constant per sec. How long will 5 g of this reactant take to reduce to 3 g ? (log 3 = ; log 5 = )