CBSE Supporting Material - 2013 For Class – XII (Chemistry)

CBSE Supporting Material - 2013

SUPPORT MATERIAL
CLASS-XII

CHEMISTRY

Contents

  • The Solid State
  • Solutions
  • Electro Chemistry
  • Chemical Kinetics
  • Surface Chemistry
  • General Principles and Processes of Isolation of Elements
  • The p- Block Elements
  • d- and f- Block Elements
  • Co-ordination Compounds
  • Haloalkanes and Haloarenes
  • Alcohols, Phenols and Ethers
  • Aldehydes, Ketones and Carboxylic Acids
  • Amines
  • Biomolecules
  • Polymers
  • Chemistry in Every Day Life

SAMPLE QUESTION

1. List four distinctions between crystalline and amorphous solids with one example of each.

2. Give suitable reason for the following–
(a) Ionic solids are hard and brittle.
(b) Copper is malleable and ductile.

3. Define F–centre. Mention its one consequence.

4. What is packing efficiency. Calculate the packing efficiency in body-centered cubic crystal.

5. Explain :
(a) List two differences between metallic and ionic crystals.
(b) Sodium chloride is hard but sodium metal is soft.

6. Account for the following :
(a) Glass objects from ancient civilizations are found to become milky in appearance.
(b) Window glass panes of old buildings are thicker at the bottom than at the top.

7. Why is graphite soft lubricant and good conductor of electricity?

8. What do you understand by the following types of stacking sequences :
(a) AB AB ............... (b) A B CABC .................
What kind of lattices do these sequences lead to?

10. Explain how much portion of an atom is located at (a) corner (b) body centre (c) face-centre and (d) edge centre of a cubic unit cell.

11. In a fcc arrangement of A and B atoms A are present at the corners of the unit cell and B are present at the face centres. If one atom of A is missing from its position at the corner, what is the formula of the compound?

12. A compound made up of elements ‘A’ and ‘B’ crystallises in a cubic close packed structure. Atoms A are present on the corners as well as face centres, whereas atoms B are present on the edge- entres as well as body centre. What is the formula of the compound? [Ans. AB]

13. Explain the terms :
(a) Intrinsic semiconductor
(b) Extrinsic semiconductor.

14. Explain how vacancies are introduced in a solid NaCl crystal when divalent cations are added to it.

15. What is meant by non-stoichiometric defect? Ionic solids which have anionic vacancies due to metal excess defect develop colour. Explain with the help of suitable example.

16. Define the term ‘point defects’ Mention the main difference between stoichiometric and non-stoichiometric point defects.

17. (i) Define molar conductivity. Draw the plots showing the variation of molar conductivity for strong and weak electrolyte with square root of concentation.
(ii) Resistance of a solution (A) is 50 ohm and that of solution (B) is 100 ohm, both solutions being taken in the same conductivity cell, if equal volumes of solutions (A) and (B) are mixed, what will be the resistance of the mixture, using the same cell? Assume that there is no increase in the degree of dissociation of (A) and (B) on mixing. [Ans. : 66.66 ohm]

18. Suggest an appropriate reason for the observation : “On increasing temperature of the reacting system by 10 degrees, the rate of reaction almost doubles or even sometimes becomes five folds.”

19. List four factors which affect the rate of a chemical reaction. State how each of these factors changes the reaction rate.

20. Differentiate between
(a) Average rate and instantaneous rate of a chemical reaction.
(b) Rate of a reaction and specific rate of reaction, i.e., rate constant.

21. What is meant by zero order reaction? Derive an integrated rate equation for a zero order reaction.

22. (a) Write two points of difference between order of reaction and molecularity of a reaction.
(b) Write one point of difference between rate of reaction and rate constant.

23. (a) Draw a plot between log k and reciprocal of absolute temperature (T).
(b) The energy of activation for a chemical reaction is 100 kJ/mol. Presence of a catalyst lowers the energy of activation by 75%. What will be effect on the rate of reaction at 20°C, if other factors are equal?

24. (a) Derive the equation for rate constant of a first order reaction. What would be the units of the first order rate constant if the concentration is expressed in moles per litre and time in seconds?
(b) For first order chemical reaction half life period (t1/2) is concentration independent. Justify the statement by using integrated rate equation.

25. Write the structures of the compounds whose names are given below :
(i) 3, 5-dimethoxyhexane-1, 3, 5-triol
(ii) cyclohexylmethanol
(iii) 2-ethoxy-3-methylpentane
(iv) 3-chloromethylpentan-2-ol
(v) p-nitroanisole

26. Describe the following reactions with example :
(i) Hydroboration oxidation of alkenes
(ii) Acid catalysed dehydration of alcohols at 443K.
(iii) Williamson synthesis
(iv) Reimer-Tiemann reaction.
(v) Kolbe’s reaction
(vi) Friedel-Crafts acylation of Anisole.

An organic compound with molecular formula C9H10O forms 2, 4, –DNP derivative, reduces Tollens’ reagent and undergoes Cannizzaro’s reaction. On vigorous oxidation it gives 1, 2-benzenedicarboxylic acid. Idenfify the compound.

Value Based Questions

(1) Smoke is colloidal solution of solid particles such as Carbon, arsenic compounds dust, etc. in air. Precipitation of smoke particles coming form the chimney of factories is carried out by Cottrel Precipitator and Carbon free air passes out through the chimney.
(a) Name the principle used in the Cottrel Precipitator.
(b) How smoke precepitator causes precipitation and settling of smoke particles.
(c) Name the value learnt by the use of this Cottrel Precipitator.

(2) While coming back from school, a student witnesses an accident on road. A person on bike had suffered injures due to skidding of bike. The student rushed to the aid of biker with the help of some people, the biker was taken to a nearby hospital. The student discovered that the bike skidded due to oil spilled on road. The student arranged for an old cloth and wiped the oil from the road.
i) Mention the values shown by the student in the above case.
ii) The oil spill can also be washed with soap and water. Explain the cleaning action of soap.

(3) Chlorofluorocarbons (CFC) and gas emitted from the exhaust system of supersonics aeroplanes might be slowly depleting the concentration of the ozone layer in the upper atmosphere.
(a) Name the gas emitted by the exhaust of supersonic jet aeroplanes.
(b) write the chemical reactions involved in the ozone layer depletion.
(c) Mention the values that are learnt by the students in this depletion of ozone layer.

(4) A student accidently spills concentrated H2SO4 on his hand. Before the teacher gets to know , his friend washed his hands with water and also with soap but the burning sensation on hand was still going on. The friend then rubs solid sodium bicarbonate on his hand and then washed with water, finally the burning sensation is releived.
(i) Mention the values shown by student’s friend.
(ii) Can you recommend any other substance available in the laboratory which can be used instead of sodium bicarbonate?
(iii) Write the chemical reaction involved in the treatment of acid burn with sodium bicarbonate.

(5) Ramu, a caretaker of swimming pool was using chlorine for disinfecting swimming pool water. His friend Jagat an another swimming pool caretaker was using ozone in place of chlorine.
(a) In your opinion, which is better way of disinfecting water in a swimming pool.
(b) Mention reason and values associated with your reply.

(6) A trainee pilot was flying his plane in stratosphere. His senior advised him not to fly the aeroplane in the stratosphere.
(a) In your opinion, why the senior pilot advised his trainee pilot not to fly his plane in the strostosphere.
(b) Write the possible chemical reaction.
(c) Mention the values associated with your reply.

(7) During world war II, mustard gas was used to kill innocent people by Adolf Hitler, though science should always be used for betterment of human race.
(i) Write the formula of mustard gas.
(ii) Name the value obtained from the above mentioned paragraph.

(8) Police usually disperse the indisciplined mob by using tear gas shells. One of the person in the mob advised the people either to use water wetted cloth on eyes or to avoid the smoke
(i) Write the chemical formula of compound used in tear gas and reaction involved.
(ii) Write the value involved as advised by one person present in the mob.

Courtesy: Edudel.nic.in

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