CBSE Class 12 2025 Chemistry 56-6-1Question Paper Set-1: Download Solutions with Answer Key

Williamson synthesis of preparing unsymmetrical ether is:

• (A) SN_1 reaction
• (B) SN_2 reaction
• (C) Electrophilic addition reaction
• (D) Elimination reaction

Which of the following compounds would be hydrolyzed by aqueous KOH most easily?

• (A) \(CH_2 = CH - Br\)
• (B) \(CH_3 - CH_2 - Br\)
• (C) \(CH_3 - CH - CH_3\)
• (D) \(CH_2 = CH - CH_2 - Br\)

According to Werner’s theory of coordination compounds:

• (A) Primary valences are ionisable.
• (B) Secondary valences are ionisable.
• (C) Both primary and secondary valences are non-ionisable.
• (D) Both primary and secondary valences are ionisable.

Which of the following complex ions is not optically active?

• (A) \([ Co(ox)_3 ]^{3-}\)
• (B) \(cis-[Co(en)_2Cl_2]^+\)
• (C) \(trans-[Co(en)_2Cl_2]^+\)
• (D) \([ Co(en)_3 ]^{3+}\)

Which of the following is the softest metal?

• (A) Zn
• (B) Sc
• (C) Cu
• (D) Fe

In the Hinsberg method for separation of primary, secondary, and tertiary amines, the reagent used is:

• (A) Nitrous acid
• (B) CHCl₃ + aq. NaOH
• (C) \(C_6H_5SO_2Cl\)
• (D) HCl / ZnCl₂

Which one of the following amines gives an alcohol on reaction with HNO₂?

• (A) \(NH_2\)
• (B) \(C_2H_5NH_2\)
• (C) \(C_2H_5NH_2\)
• (D) \(C_2H_5N_3\)

The freezing point of one molal KCl solution, assuming KCl to be completely dissociated in water, is: (\(K_f\) for water = 1.86 K kg mol\(^{-1}\))

• (A) \(-3.72^\circ C\)
• (B) \(+3.72^\circ C\)
• (C) \(-1.86^\circ C\)
• (D) \(+2.72^\circ C\)

A solution of acetone in ethanol:

• (A) obeys Raoult’s law.
• (B) forms an ideal solution.
• (C) shows a positive deviation from Raoult’s law.
• (D) shows a negative deviation from Raoult’s law.

Which of the following cell converts the energy of combustion of fuel into electrical energy?

• (A) Mercury cell
• (B) Fuel cell
• (C) Dry cell
• (D) Lead storage cell

The unit of rate and rate constant are the same for a:

• (A) First order reaction
• (B) Second order reaction
• (C) Zero order reaction
• (D) Third order reaction

Pyranose ring of glucose is formed due to the reaction between:

• (A) C\(_1\) and C\(_3\)
• (B) C\(_1\) and C\(_5\)
• (C) C\(_1\) and C\(_4\)
• (D) C\(_1\) and C\(_2\)
• (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.

Assertion (A): Actinoids show wide range of oxidation states.

Reason (R): Actinoids are radioactive in nature.

• (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): Hydrolysis of an ester follows first order kinetics.

Reason (R): The concentration of water does not get altered much during the reaction.

• (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): Boiling point of (CH₃)₃N is higher than that of CH₃CH₂CH₂NH₂.

Reason (R): Hydrogen bonding is more extensive in CH₃CH₂CH₂NH₂.

• (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): Phenol is strongly acidic as compared to ethanol.

Reason (R): Phenoxide ion is more stable than ethoxide ion.

• (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.

State Henry's law. Why are aquatic species more comfortable in cold water as compared to warm water?

Observe the graph in the given figure and answer the following questions:

(a) Write IUPAC names of the following coordination compounds:

• (i) \([ CoCl_2(en)_2]SO_4 \)
  (ii) \( K_3[Fe(C_2O_4)_3] \)
• (i) Double salt and Complex compound
  (ii) Didentate ligand and Ambidentate ligand

Draw the structures of major monohalo products in each of the following reactions:

• (a) \( CH_3C_6H_5 + HI \longrightarrow \) ?
  (b) \( C_6H_6 + Br_2 \longrightarrow \) Heat or UV light ?

How do you explain the following?

• (a) Presence of an aldehyde group in glucose.
  (b) Presence of five –OH groups in glucose.

Vapour pressure of pure water at 298 K is 24.8 mm Hg. Calculate the lowering in vapour pressure of an aqueous solution which freezes at –0.3°C. (K\(_f\) of water = 1.86 K kg mol\(^{-1}\))

The rate of a reaction:

A + B \longrightarrow \text{product

is given below as a function of different initial concentrations of A and B.



\begin{tabular{|c|c|c|c|
\hline
Experiment & [A] / mol L\(^{-1\) & [B] / mol L\(^{-1}\) & Initial Rate / mol L\(^{-1}\) min\(^{-1}\)

\hline
1 & 0.01 & 0.01 & \( 5 \times 10^{-3} \)

2 & 0.02 & 0.01 & \( 1 \times 10^{-2} \)

3 & 0.01 & 0.02 & \( 5 \times 10^{-3} \)

\hline
\end{tabular

Give reasons for the following:

• (a) The pH of aqueous NaCl increases when it is electrolyzed.
  (b) Unlike dry cell, mercury cell has a constant cell potential through its lifetime.
  (c) Conductivity of solution decreases with dilution.

(a) Answer the following about the complexes \([ FeF_6]^{3-} and [Fe(CN)_6]^{4-}\):

• (i) Write the hybridization involved in each case.
  (ii) Which of them is the outer orbital complex and which one is the inner orbital complex?
  (iii) Compare their magnetic behaviour.
  [Atomic number: Fe = 26]
• (i) What happens to the colour of complex \([ Ti(H_2O)_6]^{3+}\) when heated gradually?
  (ii) Write the electronic configuration for \(d^5\) ion if \(\Delta_o < P\).
  (iii) Write the hybridization and magnetic behaviour of the complex \([ Ni(CO)_4 ]\).
  [Atomic number: Ni = 28]

Write any two differences between SN\(_1\) and SN\(_2\) reactions. Which of the following compounds would undergo SN\(_1\) reaction faster and why?

A compound (A) with molecular formula C\(_4\)H\(_9\)N on reduction with DIBAL-H followed by hydrolysis, gives a compound (B). Compound (B) gives positive Tollens’ test but does not give iodoform test. Compound (B) can also be obtained when ethanal is treated with dilute NaOH followed by heating. Identify (A) and (B). Write the reactions of (A) with DIBAL-H followed by hydrolysis.

How will you obtain the following from aniline? Give chemical equations only.

• (a) Sulphanilic acid
  (b) Phenylisocyanide
  (c) Acetanilide

The following questions are case-based questions. Read the case carefully and answer the questions that follow.


Alcohols undergo a number of reactions involving the cleavage of C – OH bond. However, phenols do not undergo reactions involving the cleavage of C – OH bond. Alcohols are weaker acids than water. Alcohols react with halogen acids to form the corresponding haloaklanes. Phenols are stronger acids than alcohols. A characteristic feature of phenols is that they undergo electrophilic substitution reactions such as halogenation, nitration, etc. Since –OH group is a strong activating group, phenol gives trisubstituted products during halogenation, nitration, etc.


(a) What happens when phenol is treated with the following?

• (i) Br\(_2\) water
  (ii) Conc. HNO\(_3\)

The \(\alpha\)-amino acids are the building blocks of proteins. All \(\alpha\)-amino acids exist as zwitter ions due to which they show amphoteric behaviour. All amino acids are joined through peptide bonds. Proteins are broadly classified as globular proteins and fibrous proteins. Globular proteins are water soluble, whereas fibrous proteins are not. The complete structure of protein is discussed at four different levels i.e. primary, secondary, tertiary and quaternary structures. Protein loses its biological activity in denatured form.


(a) Define the following:

• (i) Peptide linkage
  (ii) Denatured protein

(a) (i) Calculate \(E_{cell}\) of a galvanic cell in which the following reaction takes place at 25°C:

\[ Zn(s) + Pb^{2+}(0.02M) \longrightarrow Zn^{2+}(0.1M) + Pb(s)
[Given: E^0_{Zn^{2+}/Zn} = -0.76V, \; E^0_{Pb^{2+}/Pb} = -0.13V, \; \log 2 = 0.3010, \; \log 4 = 0.6021, \; \log 5 = 0.6990 ] \]

(a) (i) Account for the following:

• (I) Orange colour of \(Cr_2O_7^{2-}\) ion changes to yellow when treated with an alkali.
  (II) Zn, Cd and Hg are non-transition elements.
  (III) \(E^0\) value for \(Mn^{3+}/Mn^{2+}\) couple is highly positive (+1.57 V) as compared to \(Cr^{3+}/Cr^{2+}\).
• (I) The manganate ion undergoes disproportionation reaction in acidic medium?
  (II) KMnO\(_4\) is heated?
• (i) What is ‘Misch metal’? Give its one use.
  (ii) Write the formula of an oxoanion of chromium in which it shows the oxidation state equal to its group number.
  (iii) Why does Vanadium pentoxide (V\(_2\)O\(_5\)) act as a catalyst?
  (iv) Why do transition elements have high enthalpies of atomisation?
  (v) How do you prepare Na\(_2\)Cr\(_2\)O\(_7\) from Na\(_2\)CrO\(_4\)?

(a) (i) Identify A, B, and C in the following reactions:

• (I) Carboxylic acids do not give the characteristic reactions of the carbonyl group.
  (II) Ethanoic acid is a stronger acid than ethanol.

(b) (i) Write the product(s) in the following reactions:

• (I) Wolff-Kishner Reduction
  (II) Decarboxylation Reaction