MBOSE Class 11 Question Paper 2020 for Chemistry

Total No. of Printed Pages ––11 (2)
HS/XI/Sc/Ch/20
PART –– I
2020
Choose the correct answer:
CHEMISTRY 1. The anion O– is isoelectronic with 1

( Theory ) (a) N2 

Full Marks : 70
(b) F

Time : 3 hours (c) N3


General Instructions : (d) Ne

(i) All questions are compulsory.

(ii) Question No. 1 to 5 are multiple choice questions 2. Beryllium exhibits diagonal relationship with 1
carrying 1 mark each.
(a) Boron
(iii) Question No. 6 to 10 are very short answer questions
carrying 1 mark each. (b) Aluminium

(iv) Question No. 11 to 17 are short answer questions (c) Magnesium
carrying 2 marks each. (d) Silicon
(v) Question No. 18 to 26 are long answer questions
carrying 3 marks each.
3. Magnesium is present in 1
(vi) Question No. 27 is a value based answer question
carrying 4 marks. (a) Haemoglobin

(vii) Question No. 28 to 30 are very long answer questions (b) Chlorophyll
carrying 5 marks each. (c) Vitamin B12
(viii) Use simple calculator and log table if necessary. (d) Ascorbic Acid

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(3) (4)

4. Homolytic fission of a covalent bond leads to the 9. What is dry ice? 1
formation of 1
(a) Electrophile 10. What is electromeric effect? 1

(b) Nucleophile
PART –– III
(c) Free radical

(d) Carbocation
11. The molecular mass of an organic compound is 78 and
its percentage composition is 92.4% C and 7.6% H.
Determine the molecular formula of the compound. 2
5. A person living in Shimla observed that cooking food
without using pressure cooker takes more time. The
reason for this observation is that, at high altitude: 1 12. Calculate the uncertainty in the position of an electron
if the uncertainty in its velocity is 5.7  10 5 ms –1
(a) Pressure increases (h = 6.6  10 –34 Js and mass of electron is 9.1  10 –31 kg). 2

(b) Temperature decreases
13. Give the principle involved in solvay process for the
(c) Pressure decreases manufacture of sodium carbonate. 2

(d) Temperature increases Either

14. (a) Define and explain Law of Multiple Proportion
PART –– II with suitable example. 2

6. Define molality of a solution. 1 Or

7. Give the electronic configuration of Cu (Z=29) and
Cr (Z=24). 1 (b) Calculate the molarity of NaOH in the solution
prepared by dissolving its 4.0g in enough water
to form 250ml of the solution. 2
8. Define critical temperature. 1

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(5) (6)

15. Using Markovnikov’s rule, find the product of the 1
following reactions. (ii) H2  O2  H2O, H  285 .8 kJ
2
1
(i) CH3  CH  CH2  HBr  1 (iii) C2H6  O2  2CO2  3H2O, H  1560 kJ
2
CH3
19. (a) Oxygen is more electronegative than nitrogen but
(ii) CH3  C  CH2  HCl  1 nitrogen has higher Ionisation Energy than
oxygen. Why? 1

16. Derive the Ideal Gas Equation. 2 (b) Explain why second ionisation energy of Mg is
less than that of Na? 1

Either 1
(c) Define electron gain enthalpy.
17. (a) Define hybridisation and explain taking BCl3
molecule as an example. 2
20. (a) Give the relation between Gibb’s Free energy
change and the Equilibrium constant of a reaction. 1
Or

(b) What is common ion effect? 1
(b) What is Hydrogen bonding? What are the
conditions necessary for the formation of
hydrogen bonding? 2 (c) State Le Chatelier Principle. 1

PART –– IV Either

18. (a) What is enthalpy of formation? 1 21. (a) What are hydrides? What are the different types
of hydrides? 2
(b) Calculate the enthalpy of formation of C2H6 from
the following data: 2
(b) Give one chemical reaction of H2O2 showing its
(i) C  O2  CO2 , H  393.5 kJ oxidising action in acidic medium. 1

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Or 25. (a) State the Second Law of Thermodynamics. 1
(c) Give one method of preparation of H 2O 2 with
equation. 2 (b) For the reaction, 2
(d) Write one method to remove temporary hardness
of water. 2NOCl (g) 2NO (g) + Cl2 (g), the value of the
1
equilibrium constant Kc is 3.75  10– 6 at 1069 K.
Either Calculate Kp for the reaction at this temperature.
22. (a) Explain on the basis of Molecular Orbital Theory (R=0.0831 L bar K–1 mol–1)
why O2 is paramagnetic but O22  is not. 3
Or
26. (a) Give the general electronic configuration of
(b) Discuss the shapes of the following molecules on alkaline earth metals. 1
the basis of VSEPR theory. 3
(i) NH3
(b) Define oxidation number. Find the oxidation
(ii) H2O number of Fe in K 4 FeCN6 . 1+1=2
(iii) CO3

23. (a) A microscope using suitable photons is employed PART – V
to locate an electron in an atom within a distance
of 0.1Å. What is the uncertainty, involved in the 27. Recently, different state governments are imposing a
measurement of its velocity? 2 ban on use of any kind of polythene bags. But
(b) State Pauli’s exclusion principle. polythene bags are of great use to us for packing
1
different types of materials. Can you avoid its use?
How do you agree or disagree with the government’s
24. (a) A balloon is filled with hydrogen at room decision? 4
temperature. It will burst if pressure exceeds 0.25
bar. If at 1 bar pressure the gas occupies 2.40 L
volume, upto what volume can the balloon be Either
expanded? 2
28. (a) Successive nitration in benzene takes place in
(b) What is an adiabatic process? 1 meta position. Explain why? 2

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(b) Complete the following reactions: (f) Convert the following into bond-line structure 1

Br O

Anhydrous CH3– C – CH2 – CH2 – C – OH
(i)  CH3Cl      1
AlCl3
CH3

H O / H Either
(ii) HC  CH 2  1
HgSO4

29. (a) CCl4 cannot be hydrolysed while SiCl4 can be
easily hydrolysed. Explain why? 2
(c) Give the IUPAC name of 1 (b) Complete the following reactions.

(i) H3 BO 3  1

(ii) SiO2  NaOH  1
Or

(c) What is the general electronic configuration of
(d) What is resonance? Draw the resonating structure the outer most shell in group 13 elements? 1
of nitrobenzene. 2
Or

(e) Complete the following reactions:
(d) Write two general characteristics of p–block
elements. 1
(i) CH3 CH2 Cl  alcoholic KOH  1

SO3 (e) Write the general electronic configuration of
(ii) + H2SO4  
 1
330K group 14 elements. How does diamond and
graphite differ in terms of electrical conductivity
and hardness? 1+1=2

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(f) Give one method of preparation of boric acid with
chemical equation. 2

30. (a) What are isomers? 1

(b) Give appropriate examples of the following types
of structural isomers:

(i) Functional isomers 1

(ii) Position isomers 1

(c) What is a carbocation? 1

(d) Give one example each of an electrophile and a
nucleophile. 1

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