CBSE Class 12 History (Urdu) Question Paper 2013 with Answer Key (March 4, Code - 253/1/1)

CBSE CLASS XII Questions

• 1.

  Though chlorine shows strong $-I$ effect, why is it ortho/para directing?

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• 2.

  Which isomer of $C_4H_9Br$ is most reactive towards $S_N1$ reaction?

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• 3.

  61 g benzoic acid (M = 122 g mol$^{-1}$) dissolved in 500 g benzene. Vapour pressure of pure benzene = 66 torr. Assume complete dimerisation. Calculate vapour pressure of solution.

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• 4.

  For decomposition of $H_2O_2$ by $I^-$: Step I: $H_2O_2 + I^- \rightarrow H_2O + IO^-$ (slow). Step II: $H_2O_2 + IO^- \rightarrow H_2O + I^- + O_2$ (fast). (a) Write rate law. (b) Determine order w.r.t. $H_2O_2$ and $I^-$ and overall order. (c) Molecularity of Step II.

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• 5.

  Predict the alkene that would be formed by dehydrohalogenation of 1-Bromo-1-methylcyclohexane.

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• 6.

  What are reducing sugars?

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