CBSE Class 12 Chemistry Sample Paper 2023

SECTION A
The following questions are multiple-choice questions with one correct answer. Each question carries 1 mark. There is no internal choice in this section.

1. The major product of acid catalysed dehydration of 1-methylcyclohexanol is:
a. 1-methylcyclohexane
b. 1-methylcyclohexene
c. 1-cyclohexylmethanol
d. 1-methylenecyclohexane

Answer : B

2. Which one of the following compounds is more reactive towards SN1 reaction?
a. CH₂=CHCH₂Br
b. C₆H₅CH₂Br
c. C_6H5CH (C₆H₅)Br
d. C_6H5CH(CH₃) Br

Answer : C

3. KMnO4 is coloured due to:
a. d-d transitions
b. charge transfer from ligand to metal
c. unpaired electrons in d orbital of Mn
d. charge transfer from metal to ligand

Answer : B

4. Which radioactive isotope would have the longer half- life ¹⁵O or ¹⁹O? (Given rate constants for ¹⁵O and ¹⁹O are 5.63x 10^-3 s
-1 and k = 2.38 x 10^-2s^-1 respectively.)
a. 15O
b. 19O
c. Both will have the same half-life
d. None of the above, information given is insufficient

Answer : A

5. The molar conductivity of CH3COOH at infinite dilution is 390 Scm²/mol. Using the graph and given information, the molar conductivity of CH3COOK will be: (Image)
a. 100 Scm2/mol
b. 115 Scm2/mol
c. 150 Scm2/mol
d. 125 Scm2/mol

Answer : B

5. What is the molar conductance at infinite dilution for sodium chloride if the molar conductance at infinite dilution of Na+ and Cl-ions are 51.12 × 10-4 Scm2mol and
73.54× 10-4 Scm2/mol respectively?
a. 124.66 Scm2/mol
b. 22.42 Scm2/mol
c. 198.20Scm2/mol
d. 175.78 Scm2/mol

Answer : A

6. For the reaction, A +2B→ AB2, the order w.r.t. reactant A is 2 and w.r.t. reactant B.
What will be change in rate of reaction if the concentration of A is doubled and B is halved?
a. increases four times
b. decreases four times
c. increases two times
d. no change

Answer : A

7. Arrange the following in the increasing order of their boiling points:
A : Butanamine, B: N,N-Dimethylethanamine, C: N- Etthylethanaminamine
a. Cb. Ac. Ad. B

Answer : D

8. The CFSE of [CoCl6]3- is 18000 cm^-1 the CFSE for [CoCl4] - will be:
a. 18000 cm^-1
b. 8000cm^-1
c. 2000 cm^-1
d. 16000 cm^-1

Answer : B

9. What would be the major product of the following reaction?
C6H5 -CH₂-OC6H5 + HBr  A + B
a. A= C₆H5CH2OH , B= C6H6
b. A=C₆H5CH2OH ,B= C6H5Br
c. A=C₆H5CH3 ,B= C6H5Br
d. A=C₆H5CH2Br , B= C6H5OH

Answer : D

10. Which of the following statements is not correct for amines?
a. Most alkyl amines are more basic than ammonia solution.
b. pKb value of ethylamine is lower than benzylamine.
c. CH3NH2 on reaction with nitrous acid releases NO2 gas.
d. Hinsberg’s reagent reacts with secondary amines to form sulphonamides.

Answer : C

11. Which of the following tests/ reactions is given by aldehydes as well as ketones?
a. Fehling’s test
b. Tollen’s test
c. 2,4 DNP test
d. Cannizzaro reaction

Answer : C