CBSE Class 12 Chemistry Question Paper 2026 with Solutions (Set 1 - 56/2/1)

Consider the following reaction:
\(Zn_{(s)} + Ag_2O_{(s)} + H_2O_{(l)} \rightarrow Zn^{2+}_{(aq)} + 2Ag_{(s)} + 2OH^-_{(aq)}\)
Given: \(E^\circ_{Ag^+/Ag} = 0.80~V\), \(E^\circ_{Zn^{2+}/Zn} = -0.76~V\), \(1~F = 96500~C~mol^{-1}\). \(\Delta_r G^\circ\) for the above reaction is:

• (A) \(-301.080~kJ~mol^{-1}\)
• (B) \(+310.080~kJ~mol^{-1}\)
• (C) \(-326.070~kJ~mol^{-1}\)
• (D) \(-375.060~kJ~mol^{-1}\)

Identify the correct statement:

• (A) Molecularity of a reaction is an experimental quantity.
• (B) For complex reactions molecularity has no meaning.
• (C) Molecularity of a reaction can be zero or even a fraction.
• (D) Molecularity more than three is very common in chemical reactions.

The order for the given reaction is:
\(A + 2B \rightarrow Products\)
\(Rate = k[A]^{\frac{1}{2}}[B]^1\)

• (A) 1.5
• (B) 1
• (C) 0.5
• (D) 2

Electronic configuration of chromium is:

• (A) \([Ar]~3d^4 4s^1\)
• (B) \([Ar]~3d^4 4s^2\)
• (C) \([Ar]~3d^5 4s^1\)
• (D) \([Ar]~3d^5 4s^2\)

The correct IUPAC name of the complex \([Pt(NH_3)_2Cl_2]\) is:

• (A) diamminedichloridoplatinum (IV)
• (B) diamminedichloridoplatinum (II)
• (C) dichloridodiammineplatinum (IV)
• (D) dichloridodiammineplatinum (II)

Which of the following is heteroleptic complex?

• (A) \([Co(NH_3)_6]^{3+}\)
• (B) \([Cr(NH_3)_6]^{3+}\)
• (C) \([Ni(H_2O)_6]^{2+}\)
• (D) \([Co(NH_3)_4Cl_2]^+\)

Which of the following molecules is chiral in nature?

• (A) Propan-2-ol
• (B) Butan-2-ol
• (C) 1-Bromobutane
• (D) 2-Bromopropane

Identify the correct increasing order of boiling points of the given compounds:

• (A) Propan-1-ol \(\lt \) butan-1-ol \(\lt \) butan-2-ol \(\lt \) pentan-1-ol
  
• (B) Pentan-1-ol \(\lt \) butan-1-ol \(\lt \) butan-2-ol \(\lt \) propan-1-ol
  
• (C) Propan-1-ol \(\lt \) butan-2-ol \(\lt \) butan-1-ol \(\lt \) pentan-1-ol
  
• (D) Butan-1-ol \(\lt \) butan-2-ol \(\lt \) propan-1-ol \(\lt \) pentan-1-ol

Identify the compound produced by the reduction of Ethanenitrile with Lithium aluminium hydride:

• (A) Ethylamine
• (B) Ethanal
• (C) Propylamine
• (D) Methylamine

The base which is present in DNA but not in RNA is:

• (A) Guanine
• (B) Cytosine
• (C) Thymine
• (D) Adenine

Proteins are polymers of \(\alpha\)-amino acids which are joined to each other by:

• (A) Covalent Bond
• (B) Peptide Bond
• (C) Glycosidic Bond
• (D) Coordinate Bond

Which of the following reactions is not explained by the open chain structure of glucose?

• (A) Glucose on prolonged heating with HI forms n-hexane.
• (B) Glucose reacts with hydroxylamine to form an oxime.
• (C) Glucose gets oxidized to gluconic acid on reaction with bromine water.
• (D) Glucose exists in two different crystalline forms, alpha (\(\alpha\)) and beta (\(\beta\)).

Assertion (A): The molecularity of the given reaction is 2
\(2HI \longrightarrow H_2 + I_2\)
Reason (R): Two molecules of the reactants are involved in simultaneous collision between them.

• (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• (C) Assertion (A) is true, but Reason (R) is false.
• (D) Assertion (A) is false, but Reason (R) is true.

Assertion (A): Zinc, cadmium and mercury are not considered as transition elements.
Reason (R): These elements have completely filled orbitals in their ground state as well as in their common oxidation states.

• (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• (C) Assertion (A) is true, but Reason (R) is false.
• (D) Assertion (A) is false, but Reason (R) is true.

Assertion (A): Aromatic primary amines can be prepared by Gabriel Phthalimide synthesis.
Reason (R): Aryl halides do not undergo nucleophilic substitution with the anion formed by phthalimide.

• (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• (C) Assertion (A) is true, but Reason (R) is false.
• (D) Assertion (A) is false, but Reason (R) is true.

Assertion (A): Glucose gets oxidized to six carbon gluconic acid on reaction with bromine water.
Reason (R): The carbonyl group is absent in the open chain structure of glucose.

• (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• (C) Assertion (A) is true, but Reason (R) is false.
• (D) Assertion (A) is false, but Reason (R) is true.

The concentration of the reactant is reduced from 0.6 mol \(L^{-1}\) to 0.2 mol \(L^{-1}\) in 5 minutes in a first order reaction. Calculate rate constant of the reaction. \((\log 3 = 0.48)\)

Rate constant k for the first order reaction is \(2.54 \times 10^{-3} s^{-1}\). Calculate the time required for three-fourth of the reactant to decompose. \((\log 4 = 0.60)\)

(a) Define activation energy.

(b) Write the unit of rate constant for

(i) zero order reaction, (ii) second order reaction.

(a) First ionization enthalpy of Cr is lower than that of Zn. Why ?

(b) Mention any one property of the transition elements which makes them good catalysts.

Indicate the type of isomerism exhibited by the following complex: \([Co(en)_3]Cl_3\)

Define coordination number.

(a) Draw the structure of the given compound :

4-Bromo-3-methylpent-2-ene

(b) What happens when chloroethane is treated with aqueous potassium hydroxide ?

When 1.5 g of a non-volatile solute was dissolved in 90 g of benzene, the boiling point of benzene got raised from 353.23 K to 353.93 K. Calculate the molar mass of the solute. (Given \( K_b \) for benzene = 2.52 K kg \( \mathrm{mol^{-1}} \))

Calculate emf of the following cell at 298 K:
\(Sn | Sn^{2+}(0.001~M) || H^+(0.01~M) | H_{2(g)}(1~bar) | Pt_{(s)}\)
Given: \(E^\circ_{Sn^{2+}/Sn} = -0.14~V\), \(E^\circ_{H^+/H_2} = 0.00~V [\log 10 = 1]\)

(a) Complete and balance the following equations:

(i) \( 2\mathrm{KMnO_4} \xrightarrow{513\ \mathrm{K}} \)

(ii) \( \mathrm{Na_2Cr_2O_7 + 2KCl} \longrightarrow \)

(b) Why is it difficult to separate lanthanoid elements in pure state?

(a) \( \mathrm{[Co(NH_3)_6]^{3+}} \) is diamagnetic whereas \( \mathrm{[CoF_6]^{3-}} \) is paramagnetic. Justify the statement. [Atomic number of Co = 27]

(b) Write the electronic configuration for \( d^4 \) ion if \( \Delta_0 \gt P \) on the basis of crystal field theory.

Write the reaction involved in: Rosenmund's reduction

Write the reaction involved in: Cannizzaro's reaction

Write the reaction involved in: Hell-Volhard-Zelinsky reaction

(A) Define the following term:

(a) Reducing sugar

(b) Differentiate between the following:

(i) Fibrous proteins and globular proteins

(ii) Nucleotide and nucleoside

(B) Write the reaction of glucose with the following:

(a) \( \mathrm{H_2N-OH} \)

(b) \( \mathrm{(CH_3CO)_2O} \)

(c) conc. \( \mathrm{HNO_3} \)

Osmosis is a process by which the molecules of a solvent pass from a solution of low solute concentration to a solution of high solute concentration through a semi-permeable membrane. Osmotic pressure is a colligative property. When the applied pressure on a solution exceeds its osmotic pressure, reverse osmosis occurs. When two solutions are separated by a semipermeable membrane and they have same osmotic pressure they are said to be isotonic. Of the two solutions separated by a semipermeable membrane, if one is a lower osmotic pressure, it is said to be hypotonic relative to the second solution. If it has a higher osmotic pressure, than the second solution, it is said to be hypertonic relative to the second solution. The osmotic pressure associated with the fluid inside the blood cell is equivalent to that of 0.9% (mass/volume) sodium chloride solution called normal saline solution and it is safe to inject intravenously. Osmotic pressure is vital in daily life and nature. It helps in explain, why IV fluids match blood’s osmotic pressure, its also the principle behind food preservation using salt or sugar. (a) Calculate the amount of \(CaCl_2\) (\(i = 2.59\)) dissolved in 2.46 litre of water such that its osmotic pressure is 0.70 atm at \(27^\circ C\).
\([\)Given: \(R = 0.082~L~atm~K^{-1}mol^{-1}\), molar mass of \(CaCl_2 = 111~g~mol^{-1}]\)

When raisins are kept in water, they get swollen. Name the phenomenon involved in this process.

Why osmotic pressure is more advantageous than other colligative properties?

Which phenomenon is responsible for desalination of sea water?

Why primary amines have higher boiling points than tertiary amines?

Out of Butan-1-amine and Butan-1-ol, which is more soluble in water?

(a) Give chemical tests to distinguish between the following pairs of compounds:

(i) Acetophenone and Benzophenone

(ii) Propanal and Propanone

(iii) Pentan-2-one and Pentan-3-one

(b) (i) Which of the following acids is stronger and why?

\( \mathrm{CH_2FCOOH} \), \( \mathrm{CH_3COOH} \)

(ii) Arrange the following compounds in the increasing order of their boiling points:

\( \mathrm{CH_3OCH_3} \), \( \mathrm{CH_3CH_2CH_3} \), \( \mathrm{CH_3CH_2OH} \), \( \mathrm{CH_3CHO} \)

The conductivity of \(0.1\) mol \(L^{-1}\) solution of NaCl is \(1.06 \times 10^{-2}\) S \(cm^{-1}\). Calculate its molar conductivity and degree of dissociation. (\(\lambda^\circ_{Na^+} = 50.1, \lambda^\circ_{Cl^-} = 76.5\) S \(cm^2\) \(mol^{-1}\)). (b) (i) Predict current flow direction for \(2Ag^+ + Zn \rightarrow 2Ag + Zn^{2+}\). (ii) Differentiate between primary and secondary battery.

(a) Resistance of a conductivity cell filled with 0.1 M KCl solution is 100 \(\Omega\). If the resistance of the same cell when filled with 0.01 mol L\(^{-1}\) KCl solution is 300 \(\Omega\), calculate the conductivity and molar conductivity of 0.01 mol L\(^{-1}\) KCl solution. The conductivity of 0.1 M KCl solution is \(1.29 \times 10^{-2}\) S cm\(^{-1}\).

(b) (i) Write any two advantages of \( \mathrm{H_2 - O_2} \) fuel cell.

(ii) Why does the cell potential of mercury cell remain constant throughout the life ?

An organic compound 'A', with molecular formula \(C_2H_6O\) reacts with active metals such as sodium to give compound 'B' and hydrogen gas. 'A' on treatment with iodine and sodium hydroxide gives 'C' and in presence of \(H_2SO_4\) at \(413~K\) gives 'D' (\(C_4H_{10}O\)). 'D' on reaction with excess of HI gives 'E'. Identify 'A', 'B', 'C', 'D' and 'E' and write all the reactions involved.

(a) Write the reagents which are used in the given conversions :

(i) Phenol to 2, 4, 6 - tribromophenol

(ii) Propene to propan-1-ol

(iii) Butan-2-one to butan-2-ol

(b) Explain the mechanism of acid catalyzed hydration of alkene to form corresponding alcohol.