CBSE class XII Chemsitry Important Questions *




Q. 1. Why do amines act as nucleophile?

Q. 2. Name the follwong according to IUPAC system:
CH3COCH2COCH3.

Q. 3. What are azeotropes?

Q. 4. State condition resulting in reverse osmosis.

Q. 5. Write the IUPAC names of BHC OR DDT.

Q. 6. Convert: i) Propene to propan-2-ol (ii) Anisole to phenol

Q. 7. How would you account for following:

  1. Sulpher hexafluoride is less reactive than sulphur tetrafluoride.
  2. Of the noble gases only Xe forms chemical compounds.

Q. 8. Arrange: CH3OH, (CH3)2CHOH, (CH)3-C-OH in Increasing order of

  1. Acidic strength
  2. Reactivity towards HCl.

Q. 9. Arrange RF, RCl, RBr, RI in increasing order of

  1. BP
  2. Polarity

Q. 10. Arrange the following:

  1. MF, MCl, MBr, MI (Increasing order of ionic character)
  2. NH3, PH3, AsH3, SbH3 (Increasing order of basic strength)

Q. 11. Write short notes on i) diazotization ii) Coupling.

Q. 12. Account for the following:

  1. Methyl amine has lower BP than methanol.
  2. Methyl amine is a stronger base than ammonia.

Q. 13. Write chemical equation to illustrate:

  1. Rosenmund Reduction
  2. Cannizaro Reaction
  3. Fischer Esterification.

Q. 14. Account for any two of the following:

  1. Amines are basic substances while amides are neutral.
  2. Alkyl halides have higher BP than hydrocarbons with almost same Molecular mass.
  3. Aromatic amines are weaker bases than aliphatic amines.

Q. 15. Why aniline is more reactive than benzene? Why for halogenation of aniline, it is first treated with acetic anhydride?

Or

Arrange primary, secondary, tertiary amines in increasing order of basic strength.

Q. 16. Arrange:

  1. o-methyl aniline, m-methyl aniline, p-methyl aniline, aniline and m-nitro aniline in increasing order of basic strength.
  2. o-hydroxy benzoic acid, p-hydroxy benzoic acid, m-hydroxy benzoic acid and benzoic acid (increasing order of acidic strength)

Q. 17. Explain:

  1. Gabriel pthalamide synthesis
  2. Aldol Condensation
  3. Arrange: Acetic acid, 1-chloroacetic acid, 1,1-dichloroaceic acid, 1,1,1-trichloroacetic acid in increasing order of acidic strength.

Q. 18. What is Van’t Hoff Factor? Why do some solutes show abnormal molecular masses? What is the value of Van’t Hoff Factor for

  1. Association
  2. Dissociation
  3. Non-electrolytes.

Q. 19. Account for following:

  1. Oxygen is a gas while sulphur is a solid at room temp.
  2. Nitrogen does not form NCl5 but P forms PCl5.
  3. Halogens have the smallest size in the group.

Q. 20. Distinguish between any three:

  1. Propanone and Benzaldehyde
  2. Benzaldehyde and Acetaldehyde
  3. ethanol and phenol
  4. Chlorobenzene and chloro cyclohexane

Q. 21. Convert:

  1. Ethanamine to methanamine
  2. Methanamine to ethanamide
  3. Phenol to phenolphthalein

Q. 22. Why haloalkanes undergo nucleophilic substitution rxn while haloarenes undergo electrophilic substitution rxn?

Q. 23. A 0.1539 molal aq solution of cane sugar (MM = 342gm) has a FP of 271 K while FP of pure water is 273.15K. What will be FP of a aq solution containing 5 gm of glucose (MM = 180gm) per 100 gm of solution.

Q. 24. Write short notes on

  1. Carbylamine or Riemer Teimann Rxn.
  2. Preparation of carboxylic acid from Grignard Reagent.

Q. 25. Assign Reasons for following:

  1. Acidic Strength of acids is HF
  2. SnCl4 is a liquid while SnCl2 is a solid.
  3. SnCl4is less stable than SnCl2.
  4. H3PO2 behaves as a monoprotic acid.
  5. Noble gases exhibit low chemical reactivity.

Or

  1. What are interhalogen compounds? What are their types? Give examples. Why are interhalogen compounds more recative than corresponding halogens? (3)
  2. Arrange: i) HClO, HClO2, HClO3, HClO4 (Increasing Acidic Strength)
  3. Hydrides of group 17 (Thermal stability and Reducing Character)

Q. 26. Convert:

  1. Chlorobenzene to phenol
  2. Phenol to 2-acetoxy benzoic acid
  3. Benzene to m-nitro benzene
  4. Toluene to Benzyl Chloride
  5. 2-propanol to 1-bromopropane.

Q. 27.

  1. Define Roult’s Law for a solution containing non volatile solute.(1)
  2. Explain why a mixture of ethyl alcohol and cyclohexane shows +ve deviation from Roult’s Law. (2)
  3. Arrange:1m NaCl, 1m CaCl2, 1m glucose (increasing order of elevation in BP)
  4. Give one use of reverse osmosis.
 

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