23-06-2012, 04:24 PM
CHEMISTRY FINAL EXAMINATION PAPER
CHEMISTRY FINAL EXAMINATION PAPER.pdf (Size: 80.79 KB / Downloads: 217)
1. The energies of activation for forward and reverse reactions for A2 + B2 2AB are 180 kJ mol–1 and
200 kJ mol–1 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 (A2 + B2 → 2AB) in the
presence of catalyst will be (in kJ mol–1) –
(1) 300 (2) 120 (3) 280 (4) 20
Ans. [4]
2. The cell, Zn | Zn2 (1M) | Cu2+ (1M) | Cu (Eºcell) = 1.10 V), was allowed to be completely discharged
at 298 K. The relative concentration of Zn2+ to Cu2+ [Zn ] [Cu ]
(1) Antilog (24.08) (2) 37.3 (3) 1037.3 (4) 9.65 × 104
Ans. [3]
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
Ans. [3]
4. Consider the reaction, 2A + B → Products. When concentration of B alone was doubled, the halflife
did not change. When the concentration of A alone was doubled, the rate increased by two times.
The unit of rate constant for this reaction is –
(1) L mol–1 s–1 (2) no unit (3) mol L–1s–1 (4) s–1
Ans. [1]
5. Identify the incorrect statement among the following –
(1) d-Block elements show irregular and erratic chemical properties among themselves
(2) La and Lu have partially filled d orbitals and no other partially filled orbitals
(3) The chemistry of various lanthanoids is very similar
(4) 4f and 5f orbitals are equally shielded
Ans. [4]