CBSE Class 12 Chemistry Sample Papers

Marks: 25
Duration: 1 hour

Section A: Each Question Carries 1 Mark

Question 1: Why is ferric chloride preferred over potassium chloride in case of a cut leading to bleeding?

Question 2: Among octahedral and tetrahedral crystal fields, in which case the magnitude of crystal field splitting is larger?

Question 3: How will you distinguish between phenol and cyclohexanol by suitable chemical test?

Section B: Each Question Carries 2 Mark

Question 1: Determine the molarity of an antifreeze solution containing 250g water mixed with 222g ethylene glycol (C2H6O2) (molar mass 62 g mol–1]) The density of this solution is 1.07g/mL.

Question 2: An aqueous solution containing urea was found to have boiling point more than the normal boiling point of water (373.13K). When the same solution was cooled, it was found that its freezing point is less than the normal freezing point of water (273.13K). Explain these observations.

Question 3: The conductivity of 0.20 M solution of KCl at 298 K is 0.025 S cm–1. Calculate its molar conductivity.

Section C: Each Question Carries 3 Mark

Question 1: Answer the following:
(a) Name one substance which can act as both
(i) Analgesic and antipyretic
(ii) Antiseptic and disinfectant

(b) Write the composition of Dettol.

Question 2: Answer the following:
(i) Draw the structure of phosphinic acid (H3PO2).
(ii) Write a chemical reaction for its use as reducing agent.
(iii) Suggest a quantitative method for estimation of the gas which protects us from UV rays of the sun.

Section D: Each Question Carries 5 Mark

Question 1: Answer the following:
(a) Why is chloroacetic acid more acidic than acetic acid?

(b) Write the mechanism of nucleophilic addition reaction.

(c) Give chemical tests to distinguish between the following pairs of compounds:
(i) Acetaldehyde and bezaldehyde
(ii) Propanone and propanol

Question 2: Answer the following:
(a) Write chemical equations for the following processes.
(i) Chlorine reacts with a hot concentrated solution of sodium hydroxide
(ii) Orthophosphorous acid is heated.
(iii) Pt.F6 and xenon are mixed together.

(b) Complete and Write balanced equations for the following reactions.
(i) SF4 + H2O --->
(ii) P4O10 + H2O --->