CBSE Class 12 2025 Chemistry 56-5-1 Question Paper Set-1: Download Solutions with Answer Key

The role of a catalyst is to change :

• (A) equilibrium constant
• (B) enthalpy of reaction
• (C) Gibbs energy of reaction
• (D) activation energy of reaction

Which of the following molecules is chiral in nature?

• (A) 1-chloropropane
• (B) 2-chloropropane
• (C) 1-chlorobutane
• (D) 2-chlorobutane

CH_3CH_2OH can be converted to CH_3CHO by :

• (A) catalytic hydrogenation
• (B) treatment with LiAlH_4
• (C) treatment with PCC
• (D) treatment with KMnO_4

The IUPAC name for CH_3 - CH_2 - N(CH_3) - CH_2 - CH_2 - CH_3 is :

• (A) N-methylpentan-2-amine
• (B) N-ethyl-N-methylpropan-1-amine
• (C) N,N-diethylpropan-1-amine
• (D) N,N-dimethylpropan-1-amine

A plot between concentration of reactant [R] and time ‘t’ is shown below. Which of the given order of reaction is indicated by the graph?

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

The treatment of ethyl bromide with alcoholic silver nitrite gives:

• (A) ethyl nitrite
• (B) nitroethane
• (C) nitromethane
• (D) ethene

Which of the following aqueous solutions will have the highest freezing point?

• (A) 1.0 M KCl
• (B) 1.0 M Na\textsubscript{2}SO\textsubscript{4}
• (C) 1.0 M glucose
• (D) 1.0 M AlCl\textsubscript{3}

Which of the following aldehydes will undergo Cannizzaro reaction?

• (A) CH_3 - CHO
• (B) (CH_3)_3CCHO
• (C) CH_3 - CH_2 - CHO
• (D) CH_3 - CH_2 - CH_2CHO

In which of the following groups are both ions coloured in aqueous solution?

• (A) Cu+ , Ti4+
• (B) Co2+, Fe2+
• (C) Cu+ , Fe2+
• (D) Co2+, Ti4+

CH3CH2CHO and CH3CH2COOH can be distinguished by:

• (A) Sodium bicarbonate test
• (B) Hinsberg test
• (C) Iodoform test
• (D) Lucas test

Match the type of cell given in Column I with their use given in Column II.

i. Lead storage cell > a. Wall clock

ii. Mercury cell > b. Apollo Space Programme

iii. Dry cell > c. Wrist watch

iv. Fuel cell > d. Inverter
 

While doing qualitative analysis in chemistry lab, Abhishek added yellow coloured potassium chromate solution into a test tube. He was surprised to see the colour of the solution changing immediately to orange. He realised that the test tube was not clean and contained a few drops of some liquid. Which of the following substances will be the most likely liquid to be present in the test tube before adding potassium chromate solution?

• (A) Sodium hydrogen carbonate solution
• (B) Methyl orange solution
• (C) Sodium hydroxide solution
• (D) HCl solution

Assertion (A): For measuring resistance of an ionic solution an AC source is used.

Reason (R): Concentration of ionic solution will change if DC source is used.

• (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): Henry’s law constant (K\textsubscript{H) decreases with increase in temperature.

Reason (R): As the temperature increases, solubility of gases in liquids decreases.

• (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): The solubility of aldehydes and ketones in water decreases with increase in size of the alkyl group.

Reason (R): Aldehydes and ketones have dipole-dipole interaction.

• (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): The boiling points of alkyl halides decrease in the order \(R_1 > R_3 > R_2 > R_4\).

Reason (R): The van der Waals forces of attraction decrease in the order \(R_1 > R_3 > R_2 > R_4\).

• (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.

(a) Calculate the elevation of boiling point of a solution when 3 g of CaCl\textsubscript{2} (Molar mass = 111 g mol\textsuperscript{-1}) was dissolved in 260 g of water, assuming that CaCl\textsubscript{2} undergoes complete dissociation. (K\textsubscript{b} for water = 0.52 K kg mol\textsuperscript{-1})

Based on the data given above, give plausible reason for the variation of conductivity and molar conductivity with concentration.

(a) Write the rate law expression for the reaction 2HI → H\textsubscript{2} + I\textsubscript{2}, if the order of the reaction is zero.

What is the effect of temperature on the rate of reaction? Write a mathematical expression for the same.

Explain the mechanism of acyl catalytic hydrogenation.

How can acetaldehyde be prepared from acetyl chloride?

(a) Shweta mixed two liquids A and B of 10 mL each. After mixing, the volume of the solution was found to be 20.2 mL.

(b) (i) How does sprinkling of salt help in clearing the snow covered roads in hilly areas?

(b) (ii) What happens when red blood cells are kept in 0.5% (mass/vol) NaCl solution? Justify your answer.

(b) (iii) Write an application of reverse osmosis.

For the reaction A + B \(\to\) Products, the following initial rates were obtained at various initial concentrations of reactants:

(a) What is meant by crystal field splitting energy? For a d\textsuperscript{4} ion, write the configuration if (i) \(\Delta_o\) < P, and (ii) \(\Delta_o\) > P.

Explain why in tetrahedral coordination entities, low-spin configurations are rarely observed.

Account for the following:

(a) Arrange the following compounds in the increasing order of their acidic strength:
3,5-dinitrophenol, 4-methylphenol, phenol, 2,4,6-trinitrophenol.

What happens when:
(i) Phenol is distilled with Zn dust?

Anisole is treated with HBr.

An organic compound 'A' (molecular formula C\textsubscript{6}H\textsubscript{8}O) gives 2,4-DNP test. It does not give Tollen’s test, but gives a yellow precipitate 'B' with NaOH and I\textsubscript{2}. On drastic oxidation, it gives a carboxylic acid 'C' with formula C\textsubscript{7}H\textsubscript{6}O\textsubscript{2}. Identify 'A', 'B', 'C' and write the reactions involved.

(a) Name the type of linkage responsible for the formation of proteins from \(\alpha\)-amino acids.

Write any two differences between DNA and RNA.

Give chemical reactions to show the presence of an aldehyde group and straight chain in glucose.

Define anomers.

Draw the structure of \(\beta\)-D-Glucopyranose.

Sucrose is known as invert sugar. Explain.

(a) One mole of CrCl\textsubscript{3}·4H\textsubscript{2}O precipitates one mole of AgCl when treated with excess of AgNO\textsubscript{3} solution. Write (i) the structural formula of the complex, and (ii) the secondary valency of Cr.

(b) What is the difference between a complex and a double salt?

(c) (i) Arrange the following complexes in the increasing order of their conductivity of their solution:
[Cr(NH\textsubscript{3})\textsubscript{3}Cl]\textsubscript{3}, [Cr(NH\textsubscript{3})\textsubscript{6}Cl]\textsubscript{3}, [Cr(NH\textsubscript{3})\textsubscript{5}Cl]Cl\textsubscript{2}.

(c) (ii) Write two differences between primary and secondary valences in coordination compounds.

(a) (i) For a galvanic cell, the following half reactions are given. Decide, which will remain as reduction reaction and which will be reversed to become an oxidation reaction. Give reason for your answer.

• (I) Cr^{3+} + 3e^{-} \rightarrow Cr(s); E^\circ = -0.74 V

(ii) Represent the cell in which the following reaction takes place:

\text{Mg(s) + 2Ag^{+ (0.001 M) \rightarrow \text{Mg^{2+ (0.100 M) + 2Ag(s)

Calculate E_{cell if E^\circ_{cell = 3.17 V. (log 10 = 1)

State Kohlrausch’s law. Give any two applications of it.

Given that \( \Lambda^\circ_{m} \) for NH₄Cl, NaOH, and NaCl are 129.8, 217.4, and 108.9 S cm² mol⁻¹ respectively. The molar conductivity of a 1 × 10⁻² M solution of NH₄OH is 9.33 S cm² mol⁻¹. Calculate the degree of dissociation (\( \alpha \)) of the NH₄OH solution at this concentration.

(a) (i) In a chemistry practical class, the teacher gave his students an amine 'X' having molecular formula C₂H₇N, and asked the students to identify the type of amine. One of the students, Neeta, observed that it reacts with C₆H₅SO₂Cl, to give a compound which dissolves in NaOH solution. Can you help Neeta to identify the compound 'X'?

(ii) Arrange the following in the increasing order of their pKₓ value in aqueous phase:

C₆H₅NH₂, (CH₃)₂NH, NH₃, CH₃NH₂, (CH₃)₃N

(iii) Aniline on nitration gives considerable amount of meta product along with ortho and para products. Why?

(iv) Convert aniline to:

(I) p-bromoaniline

(II) phenol

(i) Arun heated a mixture of ethylamine and CHCl3 with ethanolic KOH, which forms a foul-smelling gas. Write the chemical equation involved.

(ii) Identify A and B in the following reactions:

Convert aniline to:

(I) benzene

(II) sulphanilic acid

(a) (i) When pyrolusite ore is fused with KOH, in presence of air, a dark green coloured product ‘A’ is obtained which changes to purple coloured compound ‘B’ in acidic medium.

(II) Write the formulae of ‘A’ and ‘B’.