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All India Engineering / Architecture Entrance Examination (AIEEE)

CBSE Guess > AIEEE > AIEEE Papers > 2007 > Chemistry

AIEEE 2007 Chemistry

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Q. 1. The energies of activation for forward and reverse reactions for respectively. The presence of a catalyst lowers the activation energy of both (forward and reverse) reactions by 100 kJ mol–1. The enthalpy change of the reaction in the presence of catalyst will be (in kJ mol–1)

  1. 300
  2. 120
  3. 280
  4. 20

Sol: Enthalpy change of a reaction is not affected by the presence of a catalyst as it lowers the activation energy of the forward and reverse reaction by the same amount . None of the options given is correct but option (4) can be treated as correct in terms of magnitude. Correct choice: (4)

Q. 2. The cell, , was allowed to be completely discharged at 298 K. The relative concentration of ZnocellE

  1. antilog (24.08)
  2. 37.3

Sol:

Correct choice: (3)

Q. 3. The pKa of a weak acid (HA) is 4.5. The pOH of an aqueous buffered solution of HA in which 50% of the acid is ionized is

  1. 4.5
  2. 2.5
  3. 9.5
  4. 7.0

Sol: If the given weak acid is 50% ionized, then its conjugate base will have the concentration same as that of weak acid.

Correct choice: (3)

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