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CBSE Important Questions

CBSE Guess > Papers > Important Questions > Class XII > 2008 > Chemistry > Chemistry By Mr. Suneet Mehta


Q. 1. H2O is a liquid while H2S is a gas.

Q. 2. HF is a weak acid than HI although F is more electronegative than I.

Q. 3. Nitrogen does not form NCl5 but P forms PCl5.

Q. 4. Give example of a compound in which OS of Chlorine is +7.

Q. 5. Draw the shape of

  1. XeOF4
  2. XeO3.

Q. 6. Which compound led to the discovery of noble gas compounds?

Q. 7. Why noble gases forms compounds only with halogens?

Q. 8. Arrange: MF, MCl, MBr, MI in increasing order of ionic character.

Q. 9. Arrange: NH3, PH3, AsH3, SbH3 in increasing order of Bond strength.

Q. 10. Arrange: HClO, HClO2, HClO3, HClO4 in increasing order of acidic strength.

Q. 11. H3PO3 is diprotic.

Q. 12. OF2 should be called oxygen difluoride and not fluorine oxygen.

Q. 13. PbX2 is more stable than PbX4.

Q. 14. SnCl2 is a solid while SnCl2 is a liquid at room temp.

Q. 15. Noble gases exhibit low reactivity.

Q. 16. Arrange F2, Cl2, Br2, I2 in increasing order of Bond Energy.

Q. 17. Nitrogen exists as N2 gas while Phosphorous exists as P4.

Q. 18. Oxygen is a gas while Sulphur is a solid at room temp.


Oxygen exists as O2 while S exists as S8.

Q. 19. Arrange the halides of group no.17 in increasing order of acidic strength, boiling point, thermal stability, reducing strength, bond dissociation energy.

Q. 20. X2 is a greenish yellow gas with an offensive smell used in water purifications. It partially dissolves in water to give a solution which turns blue litmus red. When X2 is passed through NaBr solution Br2 is obtained.
Identify X2, name the group to which it belongs, write general electronic configuration, what are the products obtained when X2 reacts with H2O. Write eq. also.

Q. 21. Draw the structure of i) orthophosphoric acid ii) Sulphuric Acid

Q. 22. What is Caro’s acid?

Q. 23. Explain why halogens except F show oxidation state of +5, +3, +1 etc (3marks)

Q. 24. What are interhalogen compounds? What are their various types? Give examples of interhalogen compounds. Why are interhalogen compounds more reactive than corresponding halogens? (5)

Q. 25. Why halogens are coloured?

Q. 26. What led to the discovery of noble gases? (3)

Q. 27. How is SO2 an air pollutant?

Q. 28. Halogens have the smallest size in the group. Why?

Q. 29. Noble gases have higher atomic size than expected.

Q. 30. Fluorine has higher EA than chlorine> Explain