NEW
New Website Launch
Experience the best way to solve previous year questions with mock tests (very detailed analysis), bookmark your favourite questions, practice etc...
1

AIPMT 2010 Prelims

MCQ (Single Correct Answer)
During the kinetic study of the reaction, 2A + B $$ \to $$ C + D, following results were obtained
Run [A]/mol L$$-$$1 [B]/mol L$$-$$1 Initial rate of formation
of D/mol L$$-$$1 min$$-$$1
I. 0.1 0.1 6.0$$ \times $$10$$-$$3
II. 0.3 0.2 7.2$$ \times $$10$$-$$2
III. 0.3 0.4 2.88$$ \times $$10$$-$$1
IV. 0.4 0.1 2.40$$ \times $$10$$-$$2

Based on the above data which one of the following is correct?
A
Rate = k[A]2[B]
B
Rate = k[A][B]
C
Rate = k[A]2[B]2
D
Rate = k[A][B]2

Explanation

Rate = k[A]x [B]y

For the given situations

(I) rate = k(0.1)x (0.1)y = 6.0$$ \times $$10$$-$$3

(II) rate = k(0.2)x (0.3)y = 7.2$$ \times $$10$$-$$2

(III) rate = k(0.3)x (0.4)y = 2.88$$ \times $$10$$-$$1

(IV) rate = k(0.4)x (0.1)y = 2.40$$ \times $$10$$-$$2

Dividing eq. (I) by eq. (IV) we get

$${\left( {{{0.1} \over {0.4}}} \right)^x}{\left( {{{0.1} \over {0.1}}} \right)^y} = {{6.0 \times {{10}^{ - 3}}} \over {2.4 \times {{10}^{ - 2}}}}$$

$$ \Rightarrow $$ $${\left( {{1 \over 4}} \right)^x} = {\left( {{1 \over 4}} \right)^1}$$

$$ \Rightarrow $$ x = 1

On dividing eq. (II) by eq. (III) we get

$${\left( {{{0.3} \over {0.3}}} \right)^x}{\left( {{{0.2} \over {0.4}}} \right)^y} = {{7.2 \times {{10}^{ - 2}}} \over {2.88 \times {{10}^{ - 1}}}}$$

$$ \Rightarrow $$ $${\left( {{1 \over 2}} \right)^y} = {1 \over 4}$$

$$ \Rightarrow $$ y = 2

$$ \therefore $$ Rate = k[A][B]2
2

AIPMT 2010 Mains

MCQ (Single Correct Answer)
The rate of the reaction, 2NO + Cl2 $$ \to $$ 2NOCl is given by the rate equation rate = k[NO]2[Cl2]. The value of the rate constant can be increased by
A
increasing the temperature
B
increasing the concentration of NO
C
increasing the concentration of the Cl2
D
doing all of these.

Explanation

The value of rate constant can be increased by increasing the temperature and is independent of the initial concerntration of the reactants.
3

AIPMT 2010 Prelims

MCQ (Single Correct Answer)
For the reaction N2O5(g) $$ \to $$  2NO2(g) + 1/2O2(g)
the value of rate of disappearance of N2O5 is given as 6.25 $$ \times $$ 10$$-$$3 mol L$$-$$1 s$$-$$1. The rate of formation of NO2 and O2 is given respectively as
A
6.25 $$ \times $$ 10$$-$$3 mol L$$-$$1 s$$-$$1 and
6.25 $$ \times $$ 10$$-$$3 mol L$$-$$1 s$$-$$1
B
1.25 $$ \times $$ 10$$-$$2 mol L$$-$$1 s$$-$$1 and
3.125 $$ \times $$ 10$$-$$3 mol L$$-$$1 s$$-$$1
C
6.25 $$ \times $$ 10$$-$$3 mol L$$-$$1 s$$-$$1 and
3.125 $$ \times $$ 10$$-$$3 mol L$$-$$1 s$$-$$1
D
1.25 $$ \times $$ 10$$-$$2 mol L$$-$$1 s$$-$$1 and
6.25 $$ \times $$ 10$$-$$3 mol L$$-$$1 s$$-$$1

Explanation

N2O5(g) $$ \to $$  2NO2(g) + 1/2O2(g)

$$ - {{d\left[ {{N_2}{O_5}} \right]} \over {dt}} = {1 \over 2}{{d\left[ {N{O_2}} \right]} \over {dt}} = 2{{d\left[ {{O_2}} \right]} \over {dt}}$$

$$ \Rightarrow $$ $${{d\left[ {N{O_2}} \right]} \over {dt}} = - 2{{d\left[ {{N_2}{O_5}} \right]} \over {dt}}$$

= 2 $$ \times $$ 6.25 $$ \times $$ 10 mol l-1 sec-1

= 1.25 $$ \times $$ 10$$-$$2 mol L$$-$$1 s$$-$$1

$${{d\left[ {{O_2}} \right]} \over {dt}} = - {1 \over 2}{{d\left[ {{N_2}{O_5}} \right]} \over {dt}}$$

= $${{6.25 \times {{10}^{ - 3}}} \over 2}$$

= 3.125 $$ \times $$ 10$$-$$3 mol L$$-$$1 s$$-$$1
4

AIPMT 2009

MCQ (Single Correct Answer)
Half-life period of a first order reaction is 1386 seconds. The specific rate constant of the reaction is
A
0.5 $$ \times $$ 10$$-$$2 s$$-$$1
B
0.5 $$ \times $$ 10$$-$$3 s$$-$$1
C
5.0 $$ \times $$ 10$$-$$2 s$$-$$1
D
5.0 $$ \times $$ 10$$-$$3 s$$-$$1.

Explanation

Specific rate constant

k = $${{0.693} \over {{t_{1/2}}}}$$

= $${{0.693} \over {1386}}$$

= 0.5 $$ \times $$ 10-3 sec-1

Joint Entrance Examination

JEE Main JEE Advanced WB JEE

Graduate Aptitude Test in Engineering

GATE CSE GATE ECE GATE EE GATE ME GATE CE GATE PI GATE IN

Medical

NEET

CBSE

Class 12