Chemical Kinetics Test

Result

Chemical Kinetics Test - 69

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Question 1
1 / -0

If the activation energy is 65 kJ then how much time faster a reaction proceed at $${ 25 }^{ o }C$$ than $${ 0 }^{ o }C$$?

A
12

B
11

C
13

D
15

Solution
Question 2
1 / -0

Thermal decomposition of a compound is of first order. If $$50$$ percent of a sample of compound is decomposed in $$120$$ mins, how long will it take for $$90$$ percent of compound to decompose?

A
$$299$$ mins.

B
$$399$$ mins.

C
$$99$$ mins.

D
$$9.9$$ mins.

Solution

According to half time period
$$k=\dfrac{0.693}{{{t}_{\dfrac{1}{2}}}}$$
$$\Rightarrow \dfrac{0.693}{120}=5.77\times {{10}^{-3}}{{\min }^{-1}}$$
Here,
$$\left( {{t}_{\dfrac{1}{2}}}=120\ \min t \right)$$

Now a first order reaction

$$k=\dfrac{2.303}{t}\log \dfrac{1}{a-x}$$
$$a=100,\ x=90$$

$$\therefore \ \ 5.77\times {{10}^{-3}}=\dfrac{2.303}{t}\log \dfrac{100}{100-90}$$
$$ t=\dfrac{2.303}{5.77\times {{10}^{-3}}}\log 10 $$
$$ =399\ \min . $$
This is the required answer.
Question 3
1 / -0

For a 1st order reaction: $$A\rightarrow Products$$; the rate of reaction at $$[A]=0.2M$$ is $$1\times {10}^{-3}$$ $$mol$$ $${L}^{-1}s^{-1}$$ reaction will be $$75$$% completed in

A
$$138.6s$$

B
$$277.2s$$

C
$$442s$$

D
$$822s$$

Solution
Question 4
1 / -0

The activation energy of a certain uncatalysed reaction at $$300K$$ is $$76kJ{mol}^{-1}$$. The activation energy is lowered by $$19kJ{mol}^{-1}$$ by the use of catalyst. By what factor, the rate of catalysed reaction is increased?

A
$${e}^{4.6}$$

B
$${e}^{5.6}$$

C
$${e}^{6.6}$$

D
$${e}^{7.6}$$

Solution
Question 5
1 / -0

For the equilibrium, $$Ag \rightleftharpoons B(g),\Delta H$$ is $$-40kJmol^{-1}$$. If the ratio of activation energies of the forward $$(E_{f})$$ and $$(E_{b})$$ reaction is $$(2/3)$$ then:

A
$$E_{f}=60KJ \ mol^{-1}:E_{b}=100kJ\ mol^{-1}$$

B
$$E_{f}=30KJ \ mol^{-1}:E_{b}=70kJ\ mol^{-1}$$

C
$$E_{f}=80KJ \ mol^{-1}:E_{b}=120kJ\ mol^{-1}$$

D
$$E_{f}=70KJ \ mol^{-1}:E_{b}=30kJ\ mol^{-1}$$

Solution
Question 6
1 / -0

A reaction proceeds through the formation of an intermediate B in a unimolecular reaction

The integrated rate law for this reaction is?

A
$$[A] = [A]_0e^{-k_at}$$

B
$$[A] = [A]_0(e^{-k_at} - e^{-k_bt})$$

C
$$[A] = \dfrac{[A]_0}{2}(1 + \dfrac{k_a e^{-k_b t} - k_b e^{-k_a t}}{k_a - k_b})$$

D
$$[A]= [A]_0(1 + e^{-k_a t} - e^{-k_b t})$$

Solution
Question 7
1 / -0

$$SO_2CI_2\rightleftharpoons SO_2+CI_2$$ is the first order as gas raection with $$K=2.2\times10^{-5} sec^{-1}$$ at $$320^oC$$.The percentage of $$SO_2CI_2$$ decomposed on heating for 90 minutes is

A
$$1.118$$

B
$$0.1118$$

C
$$18.11$$

D
$$11.30$$

Solution
Question 8
1 / -0

The rate equation for the reaction 2A+B $$\longrightarrow $$C is rate =K[A][B].
the correct statement about this is :

A
K is independent of [A] and [B]

B
$${t}_{1/2}$$ is constant

C
Unit of K is $${sec}^{-1}$$

D
Rate of formation of C is twice the rate of disappearance of A

Solution
Question 9
1 / -0

A reaction requires 60 minutes and 20 minutes to complete 50% at $$27^o C$$ and $$47^oC$$ respectively. calculate activation energy of the reaction.

A
$$45678$$ cal

B
$$26789$$ cal

C
$$10480$$ cal

D
None of these

Solution
Question 10
1 / -0

An adiabatic container fitted with a movable adiabatic piston (operating at 1 atm ) is filled with 2 litre of 2 M $$H_2O_2 $$(aq) solution at 300 K. If $$H_2O_2$$ dissociates following first order decay with a half life of 10 min then change in internal energy in first 20 min will be [R = 2 cal/mol K.]:

A
900 Cal

B
450 Cal

C
1800 Cal

D
225 Cal

Solution