MBOSE Class 11 Question Paper 2023 for Chemistry

Total No. of Printed Pages ––11 (2)
HS/XI/Sc/Ch/23
PART –– I
2023
Choose the correct answer: 1 5 = 5
CHEMISTRY 1. Considering the elements B, Al, Mg and K the correct
order of their metallic character is : 1
( Theory )
(a) B  Al  Mg  K

Full Marks : 70 (b) Al  Mg  B  K
Time : 3 hours (c) Mg  Al  K  B
General Instructions : (d) K  Mg  Al  B
(i) All questions are compulsory.

(ii) Question No. 1 to 5 are multiple choice questions 2. The % by mass of carbon in methane is: 1
carrying 1 mark each.
(a) 25%
(iii) Question No. 6 to 10 are very short answer questions (b) 50%
carrying 1 mark each.
(c) 75%
(iv) Question No. 11 to 17 are short answer questions
carrying 2 marks each. (d) 100%

(v) Question No. 18 to 26 are long answer questions
carrying 3 marks each. 3. Which of the following has the highest dipole moment? 1

(vi) Question No. 27 is a value based answer question (a) NH 3
carrying 4 marks.
(b) NF3
(vii) Question No. 28 to 30 are very long answer questions
carrying 5 marks each.
(c) BF3
(viii) If necessary simple calculator and log table can be
used. (d) BeCl 2

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(3) (4)

4. An electrophillic reagent is: 1 9. What type of a chemical reaction attain a state of
equilibrium when carried out in a closed vessel? 1
(a) Electron deficient species

(b) Electron rich species
10. Give the IUPAC name of Cl 1
(c) Negatively charged species

(d) A Lewis base NO2
O 2N

5. The empirical formula and molecular mass of a
compound are CH2O and 180g respectively. What will PART –– III
be the molecular formula of the compound? 1
(a) C9H18O 9 11. Determine the empirical formula of an oxide of iron
which has 69.9% iron and 30.1% oxygen by mass. 2
(b) CH2O

(c) C6H12O 6 12. Derive de-Broglie equation. 2

(d) C2 H4 O 2
13. Define (i) Entropy and (ii) Gibb’s free energy 2

PART –– II
14. Either

6. How do you express the bond length in terms of bond (a) Define and explain the law of multiple proportion
order? 1 with suitable example. 2

Or
7. Define molarity of a solution. 1
(b) How many moles of nitrogen will be needed to
8. Write down the electronic configuration of Cr (Atomic produce 8.2 moles of ammonia by reaction with
no.24). 1 hydrogen. 2

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(5) (6)

15. (a) Why does BF3 behave as Lewis acid? 1 20. (a) Find out the oxidation number of the underlined
elements in each of the following species. 1
(b) Define Octet rule. 1
(i) K ClO3 (ii) Fe(CN)6 4
16. Derive the relation : H  U  pV 2 (b) Write the expression for the equilibrium constant,
Kc of the following reaction. 1

2NOCl(g) 2NO(g)  Cl2 (g)
17. Either
(a) Explain the shapes of the following on the basis (c) What is common ion effect? 1
of VSEPR theory. 2
(i) BeCl2 (ii) PCl5
Or
21. Either
(b) Define Intermolecular and Intramolecular
hydrogen bonding with examples. 2
(a) Ionization enthalpy of Nitrogen is more than that
of oxygen. Give reason. 2
PART –– IV
(b) Why electrons are first filled up in the 4s orbital
18. (a) Give the relationship between standard free and then the 3d orbital in writing electronic
energy change and equilibrium constant. 1 configuration of atoms? 1
(b) State First Law of Thermodynamics and derive
its mathematical expression. 2 Or

(c) Among the elements B, Al, C and Si which has
19. (a) An atomic orbital has n=3. What are the possible the most negative electron gain enthalpy? 1
values of l and ml ? 1
(b) How many protons, electrons and neutrons are (d) How do atomic radius vary in a period and in a
there in 25
12 Mg ? 2 group? How do you explain the variation? 2

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(7) (8)

22. Either 25. Either
(a) Permanganate ion reacts with iodide ion in acidic (a) Write Lewis dot symbols for the following atom
medium to give Manganese ion and iodine. Write and ion.
a balanced chemical equation for the reaction by 1
oxidation number method/ion electron method. 3 (i) S 2– (ii) Al
Or
(b) What is a Buffer solution? Give examples. 2
(b) Define Oxidation and Reduction in terms of
electronic concept with suitable example. 3 Or

(c) What is the total number of  and  bonds in
the following molecules? 1
23. (a) What will be the wavelength of a ball of mass 0.1kg
moving with a velocity of 10ms–1. 1 (i) HC  CH (ii) CH3COOH

(b) What are Isotopes and Isobars? 2 (d) What is the effect of increasing pressure on the
equilibrium? 2

N2(g) + 3H2(g) 2NH3(g)
24. (a) The equilibrium constant expression for a gas
reaction is 1
[NH3 ]4 [O2 ]5
Kc  26. (a) Explain Isoelectronic species with examples. 2
[NO]4 [H2O]6
Write the balanced chemical equation (b) State Hess’s Law of Constant Heat Summation. 1
corresponding to this expression.

(b) Calculate Kc for the reaction: 2 PART – V
2SO3(g) 2SO2(g) + O2(g)

for which K p  3.5  10 23 atm at 27oC 27. –NO2 group attached to benzene ring is meta directing
whereas –OH group is ortho and para directing. Why? 4
Given R = 0.082 L atm mol–1 K–1.

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(9) ( 10 )

28. Either (e) Assign E–Z system to the following compounds 1

(a) Give a complete structural formula of the following
(i) (ii)
compounds. 3
O
(i)

(f) Give the correct order of stability of the following
CN alkyl free radicals. 1
(ii)
   
O C H(CH 3 )2 , C H2CH 3 , C(CH 3 )3 , C H3

(iii)
Cl H

29. Either

(b) Which of the following compounds are aromatic (a) Define Rearrangement reaction and Isomerisation
according to Huckel rule? 1 reaction with examples. 3

(i) (ii) (b) What is  – elimination reaction? 1

(c) What are carbenes? 1
(c) Give the hybridisation state of the underlined
Carbon atom in the following molecules. 1 Or

(i) CH3 CN (ii) CH3 CH  CHCH3
(d) What are Carbocations and Carbanions? 3
Or
(e) Write down the Resonance structure of Aniline. 1
(d) Explain Inductive effect and Electromeric effect
with suitable examples. 3 (f) Write bond line formula of Isopropyl alcohol. 1

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( 11 )

30. (a) What happens when benzene is treated with
chlorine in the presence of anhydrous AlCl3?
(Give equation only) 1

(b) Complete the reaction: 1
(i) CaC 2  2H2O 
Peroxide
(ii) CH3  CH  CH2  HBr    1

(c) Explain Geometrical Isomerism with suitable
examples. 2



HS/XI/Sc/Ch/23