1
AIPMT 2007
MCQ (Single Correct Answer)
+4
-1
If 60% of a first order reaction was completed in 60 minutes, 50% of the same reaction would be completed in approximately
(log 4 = 0.60, log 5 = 0.69)
A
45 minutes
B
60 minutes
C
40 minutes
D
50 minutes
2
AIPMT 2007
MCQ (Single Correct Answer)
+4
-1
In a first-order reaction A $$ \to $$ B, if k is rate constant and initial concentration of the reactant A is 0.5 M, then the half-life is
A
$${{\log 2} \over k}$$
B
$${{\log 2} \over {k\sqrt {0.5} }}$$
C
$${{\ln 2} \over k}$$
D
$${{0.693} \over {0.5k}}$$
3
AIPMT 2007
MCQ (Single Correct Answer)
+4
-1
The reaction of hydrogen and iodine monochloride is given as :
H2(g) + 2ICl(g) $$ \to $$ 2HCl(g) + I2(g)
This reaction is of first order with respect to H2(g) and ICl(g),
following mechanisms were proposed.

Mechanism A :
     H2(g) + 2ICl(g) $$ \to $$ 2HCl(g) + I2(g)
Mechanism B :
     H2(g) + ICl(g) $$ \to $$ HCl(g) + HI(g) ; slow
     HI(g) + ICl(g) $$ \to $$ HCl(g) + I2(g) ; fast

Which of the above mechanism(s) can be consistent with the given information about the reaction?
A
A and B both
B
Neither A nor B
C
A only
D
B only
4
AIPMT 2007
MCQ (Single Correct Answer)
+4
-1
Consider the following reactions :
(i) H+(aq) + OH$$-$$(aq) = H2O(l),  $$\Delta $$H = $$-$$ X1 kJ mol$$-$$1
(ii) H2(g) + 1/2O2(g) = H2O(l),   $$\Delta $$H = $$-$$ X2 kJ mol$$-$$1
(iii) CO2(g) + H2(g) = CO(g) + H2O(l),  $$\Delta $$H = $$-$$ X3 kJ mol$$-$$1
(iv) C2H2(g) + 5/2O2(g) = 2CO2(g) + H2O(l),    $$\Delta $$H = +X4 kJ mol$$-$$1

Enthalpy of formation of H2O(l) is
A
+X3 kJ mol$$-$$1
B
$$-$$X4 kJ mol$$-$$1
C
+X1 kJ mol$$-$$1
D
$$-$$X2 kJ mol$$-$$1
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