CBSE Class 12 Chemistry Question Paper 2004 Delhi Set 56 3

CBSE CLASS XII Questions

• 1.

  A reaction \( \mathrm{A \rightarrow B} \) follows second order kinetics. How will the rate of reaction be affected if the concentration of (i) A is increased by three times, and (ii) A is reduced to half ?

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• 2.

  Consider the decomposition of hydrogen peroxide \( (\mathrm{H_2O_2}) \) as per the equation given below : \[ 2\mathrm{H_2O_2} \xrightarrow[\text{Alkaline medium}]{I^-} 2\mathrm{H_2O} + \mathrm{O_2} \] The mechanism for this reaction was found to be : Step I : \( \mathrm{H_2O_2} + I^- \longrightarrow \mathrm{H_2O} + IO^- \) (slow) Step II : \( \mathrm{H_2O_2} + IO^- \longrightarrow \mathrm{H_2O} + I^- + \mathrm{O_2} \) (fast) (a) Write the rate law expression. (b) Determine the order of reaction with respect to \( \mathrm{H_2O_2} \), \( I^- \) and overall order of reaction. (c) What is the molecularity of the reaction in Step II ?

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• 3.

  Match Column I with Column II and choose the correct option :

  Column I	Column II
  a. Osmotic pressure	i. \( \Delta \mathrm{T_f} = \mathrm{K_f}\,m \)
  b. Elevation of boiling point	ii. \( \pi = CRT \)
  c. Depression of freezing point	iii. \( \frac{\mathrm{P_1^0 - P_1}}{\mathrm{P_1^0}} = \frac{\mathrm{W_2 \times M_1}}{\mathrm{M_2 \times W_1}} \)
  d. Relative lowering of vapour pressure	iv. \( \Delta \mathrm{T_b} = \mathrm{K_b}\,m \)

  • a-i, b-ii, c-iii, d-iv
  • a-ii, b-i, c-iii, d-iv
  • a-iv, b-iii, c-ii, d-i
  • a-ii, b-iv, c-i, d-iii
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• 4.

  An organic compound (X) has the molecular formula \(C_5H_{10}O\). Draw structures for (X) if it:
  (I) does not give Tollen's test but gives a positive iodoform test.
  (II) does not give Tollen's test and iodoform test but undergoes Aldol condensation.
  (III) undergoes Cannizzaro's reaction.
  

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• 5.

  Draw the structures of major monohalo products in each of the following :

  (a)

  (b)

  
  

  

  
  

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• 6.

  Conductivity of \( 2.5 \times 10^{-4} \) M methanoic acid solution is \( 5.25 \times 10^{-5} \) S cm\(^{-1}\).

  (a) Calculate its molar conductivity.

  (b) Calculate its degree of dissociation.

  [Given : \( \lambda^{\circ}_{(\mathrm{H^+})} = 349.5 \) S cm\(^2\) mol\(^{-1}\) and \( \lambda^{\circ}_{(\mathrm{HCOO^-})} = 50.5 \) S cm\(^2\) mol\(^{-1}\)]

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