CBSE Papers, Questions, Answers, MCQ ...
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CBSE class XII Chemistry Important Questions **
Q. 1. Define activation energy of a reaction.
Q. 2. A cubic solid is made of two elements X and Y. Atoms Y are at the corners of the cube and X at the body centre. What is the formula of the compound?
Q. 3. State two main functions of carbohydrates in sugarcane.
Q. 4. Why is HF not stored in plain glass bottles?
Q. 5. State one use of acetonitrile.
Q. 6. What values of quantum number, m are permitted for an electron having angular quantum number, 1 = 2 ?
Q. 7. Which types of crystals exhibit piezoelectricity?
Q. 8. What is Tyndall effect?
Q. 9. How many effective sodium ions are located at the centres of faces of a unit cell in a sodium chloride crystal?
Q. 10. Name the first element of 3 d transition metal series.
Q. 11. What are inner transition metals?
Q. 12. State second law of thermodynamics.
Q. 13. Name a direct dye.
Q. 14. Sketch the zwitter ion form of amino acetic acid.
Q. 15. Mention an industrial product manufactured from methanal.
Q. 16. How does a fuel cell operate?
Q. 17. Mention two important uses of methanol.
Q. 18. What is the importance of amino acids to us?
Q. 19. Give an example of associated colloids.
Q. 20. Define order of a reaction.
Q. 1. Zn, Cd and Hg are not considered as transition metals.
Q. 2. Cu,Ag &Au are considered as transition metal though it has 3d,10 configuration.
Q. 3. Zn, Cd and Hg are volatile and Hg is a liquid metal.
Q. 4. Transition metals have high enthalpy of atomisation.
Q. 5. 4d and 5d elements have higher enthalpy of atomisation than 3d elements.
Q. 6. Density of 3d elements increases from Sc to Ni.
Q. 7. Atomic and ionic radii generally decrease along the period.
Q. 8. Zr and Hf have similar size.
Q. 9. Transition metals do not show regular variation of ionisation enthalpies.
Q. 10. 5d elements have higher ionisation enthalpy than 3d and 4d elements.
Q. 11. Generally first ionisation enthalpy increases along the period.
Q. 12. Cr &Cu has higher second ionisation enthalpy (Cr = 24,Cu = 29)
Q. 13. Mn &Zn has higher 3rd ionisation enthalpy (Mn = 25 Zn = 30)
Q. 14. Cu, Ni and Zn normally do not exhibit oxidation state higher than +2.
Q. 15. Transition metals show variable oxidation state.
Q. 16. Transition metals do not show regular variation of E0 values.
Q. 17. E0 Mn3+/Mn2+ have higher +ve value than E0 Cr3+/Cr2+.(Cr=24 Mn=25).
Q. 18. E0 Zn2+/Zn has higher – value. ( Zn = 30).
Q. 19. Transition metals form complexes easily.
Q. 20. Transition metals act as catalysts.
Q. 21. Transition metal compounds are paramagnetic.
Q. 22. Sc3+,Cu+ and Zn2+ are diamagnetic .Sc=21 Cu=29 Zn=30).
Q. 23. Oxidation state of transition metals increases by one unit.
Q. 24. E0 Ni2+/Ni has higher – ve value.
Q. 25. Transition metal compounds are coloured.
Q. 26. Sc3+, Cu+ and Zn2+ are colourless .[Sc = 21 Cu = 29 Zn = 30].
Q. 27. Transition metals form interstitial compounds easily.
Q. 28. Transition metals form alloys easily.
Q. 29. Higher oxides of transition metals are acidic.
Q. 30. Enthalpy of atomization of transition metals reaches a maximum in the middle of each series
Q. 31. Lanthanoid ions are coloured and paramagnetic.
Q. 32. La3+ and Lu3+ are colourless and diamagnetic. (La=57 Lu=71).
Q. 33. Ln are paramagnetic.
Q. 34. La3+ is diamagnetic.
Q. 35. Ce is stable in +4 oxidation state. E0 Ce4+/Ce3+ has higher positive value.
Q. 36. Eu2+ is a good reducing agent.(Eu=63).
Q. 37. Ce4+ is a good oxidising agent .
Q. 38. Yb2+ is stable. It acts as a reducing agent. (Yb=70).
Q. 39. In lanthanoid hydroxide M(OH)3 basic character decreases with increase in atomic number.
Q. 40. Actinoids show greater range of oxidation state than lanthanoids.
Q. 41. Actinoid contraction is greater than lanthanoid contraction.
Q. 42. Ionisation enthalpies of early actinoids are lesser than that of early lanthanoids.
Q. 43. In the d4 species Mn3+ is an oxidising agent where as Cr2+ is a reducing agent
Q. 44. Co(II) is stable in aqueous solution but get oxidised in the presence of complexing agents.
Q. 45. d1 configuration is unstable in transition metals.
Q. 46. Transition metals exhibit higher oxidation state in oxides and flourides.
Q. 47. Zn has lowest enthalpy of atomisation.
Q. 48. First ionization enthalpy of Cr is lower while Zn is higher.(Cr=24, Zn=30)
Q. 49. Zn has lower second ionization enthalpy.
Q. 50. Number of oxidation states at the extreme ends of 3d transition metals are very few.
Q. 51. Transition metals in higher oxidation states are more stabilized in oxides than in fluorides.
Q. 52. E0 Cu2+/Cu is positive.
Q. 53. E0 Sc3+/Sc2+ has lower value (Sc = 21)
Q. 54. E0 Zn3+/Zn2+ have higher positive value.
Q. 55. E0 Fe3+/Fe2+ has comparatively lower positive value than E0 Mn3+/Mn2+ (Mn=25, Fe=26)
Q. 56. E0 V3+/V2+ have negative value (V=23)
Q. 57. Cu2+ (aq) is more stable than Cu+ (aq) despite the d10 configuration of Cu+
Q. 58. Highest fluoride of Mn is MnF4 while highest oxide is Mn2O7.
Q. 59. Oxidising power of Oxides VO2+ <>2O72- <>4-
Q. 60. KMnO4 titration is not carried out using HCl as acid medium.
Q. 61. Third ionization enthalpy of La, Gd and Lu are abnormally low( La = 57, Gd = 64, Lu = 71)
Q. 62. 5f electrons can take part in bonding to a greater extent than 4f electron though both have similar angular wave function.
Q. 63. Highest oxidation state is exhibited by oxoanion in transition metals.
Q. 64. Generally negative value of E0 M2+/M decreases across the series of 3d elements.
Q. 65. It is unsatisfactory to review the chemistry of actinoids in terms of oxidation state.