Class XI Chemistry Practice Paper

Central Board of Secondary Education

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CHEMISTRY

CLASS-XI

Time Allowed: 3 hours Maximum Marks: 70

 

General Instructions:

I) All questions are compulsory.

ii) Question number 1 to 8 are short answer questions and carry 1mark each.

iii) Question number 9 to 18 are short answer questions and carry 2 marks each.

iv) Question number 19 to 27 are also short answer questions and carry 3 marks each.

v) Question number 28 to 30 are long answer questions and carry 5 marks each.

vi) Use log tables if necessary

1. Write the electronic configuration of Fe3+ ion (Atomic number of Iron = 26).

2. Why does boron form electron deficient compounds?

3. Tertiary carbocation is more stable than Secondary. Explain why?

4. How does molarity change with temperature?

5. Write the IUPAC name of tertiary butyl alcohol.

6. An atomic orbital has l=2.What are the possible values of m?

7. Find out the oxidation number of manganese in MnO4- and MnO42-.

8. Carbon shows the property of catenation remarkably. Assign a reason for this statement.

9. Write any two points of differences between sigma and pi bond.

OR

a) How many sigma and pi bond are present in the molecule:

CH2=CH-CH=CH2.

b) Which type of hybrid orbital is used by the second carbon atom in the following molecule.

CH≡C-CH2-CH=CH2

10. What is the density of SO2 gas at 27oC. (Atomic Weights: S=32, O=16, R=0.0821l/K/mol.

11. What happens when

a) Lead sulphide is reacted with hydrogen peroxide solution.

b) Chlorine reacts with milk of lime. Write chemical equations for reactions involved.

12. Why do real gases deviate from the ideal behaviour? What are the conditions under which real gases show ideal behaviour?

13. The mass of an electron is 9.1×10-31 Kg. If its kinetic energy is 3×10-25 J, calculate its wavelength.

14. Account for the following

a. The first ionization enthalpy of Mg is greater than that of Al.

b. Oxygen has a lower electron gain enthalpy than sulphur.

15. Calculate the bond order of O2+ and O22- molecular ions and predict their magnetic behaviour.

16. Explain the following:

a. Wurtz reaction

b. Huckles Rule

17. Account for the following :

a. Pentane has higher melting point than 2-methyl butane.

b. Ethyne is more acidic than ethane.

18. What are electrophiles and neucleophiles? Give one example of each.

19. Write the net ionic equation for the reaction of potassium dichromate(VI) with sodium sulphite in an acid solution to give chromium(III) ion and the sulphate ion.

OR

Permanganate (VII) ion in basic solution oxidises iodide ion to produce iodine and manganese dioxide. Write a balanced ionic equation to represent this redox reaction.

20. Write short notes on :

a. Photochemical Smog

b. Ozone Hole

c. Acid Rain

21. a. How will you prepare hydrogen peroxide by industrial method.

b. What happens when

i. ionic hydrides are treated with water?

ii. Boron tri-fluoride reacts with sodium hydride?

22. a. Define the term conjugate acid-base pair.

b. The value of Kc for the reaction 2A↔B+C is 2×10 -3 at 500K at a given time. The composition if reaction mixture is [A]=[B]=[C]= 3×10-4 M. Is the reaction mixture at equilibrium? If not, what is the direction of net reaction?

23. State Le-Chatelier’s Principle. What are its applications in the manufacture of Ammonia in Habers Process?

24. How will you detect the presence of nitrogen in Lassaigne’s Test .

During estimation of nitrogen by kjeldahl’s method the ammonia evolved from 0.5g of the compound neutralised 10ml of 1M H2SO4.Find out the percentage of nitrogen in the compound.

25. Draw the structure of:

a. Di-borane

b.AlCl3

C.BeCl2 in solid state

26. a. What do you understand by common ion effect?

b. Determine the solubility of barium sulphate in 0.05M in barium chloride solution.(Ksp-BaSO4=1.1×10-10).

27. Why lithium shows anomalous behaviour in the group. Give two points of similarities between lithium and magnesium.

28. Explain the following with suitable examples:

a. Inductive Effect.

b. Resonance Effect.

c. Hyper-conjugation.

OR

Define Isomerism. Explain the type of isomerism shown by

a. But-2-ene.

b. Conformations of Ethane.

29. a. SiF6 2- is known where as SiCl6 2- is not. Give possible reason.

b. Why is boric acid considered as a weak acid?

c. What are silicones?

d. CCl4 does not hydrolyse unlike SiCl4.

e. Tl(1) compounds are more stable than Al(1) compounds. Give reasons.

OR

a. Why does BCl3 act as a Lewis acid?

b. What is dry-ice? Why is it so called?

c. What is water gas? How is it prepared?

d. Which is the basic building unit of all silicates?

e. What are zeolites?

30. How will you bring about the following conversions?

i. Propene to 1- bromo-propane.

ii. Benzene to acetophenone.

iii.Ethyne to acetaldenhyde.

iv.Ethene to formaldehyde.

v.Sodium Benzoate to Benzene.

OR

What happens when

a. Ethyne gas is allowed to pass over red hot iron tube.

b. Calcium carbide is treated with water.

c. Propene is treated with dilute KMnO4.

d. Benzene is treated with chlorine in presence of UV light.

e. Phenol is treated with heated zinc dust.

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