Chemical Kinetics Test

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Chemical Kinetics Test - 17

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Weekly Quiz Competition

Question 1
1 / -0

For the reaction shown, which best describes the elementary reaction?

$$2N_{2}O_{5}\leftrightharpoons 4NO_{2} + O_{2}$$

A
First order unimolecular

B
Second order unimolecular

C
Second order bimolecular

D
First order bimolecular

Solution

Since decomposition of $$N_2O_5$$ is taking place and only one reacting species in the given reaction so it is unimolecular. And since it is a elementary reaction therefore molecularity = order = 1.
Question 2
1 / -0

For zero order reaction, the integrated rate equation is:

A
$$kt=\cfrac{[A]}{[A]_o}$$

B
$$kt=[A]-[A]_o$$

C
$$[A]=-kt+[A]_o$$

D
$$[A]=kt-[A]_o$$

Solution

For Zero order reaction, the integrated rate rquation is

$$[A] = -kt + [{A}]_{0}$$
Question 3
1 / -0

Half life for a Ist order reaction $${ A\longrightarrow }$$ product , is 60minute. What % of A remains after120min?

A
25 %

B
50%

C
75%

D
90%

Solution
Question 4
1 / -0

In the first order reaction $$75$$% of the reactant disappeared in $$1.38$$ h, the rate constant of the reaction is:

A
$$3.6$$ x $$10^{-3}$$ $$s^{-1}$$

B
$$2.8$$ x $$10^{-4}$$ $$s^{-1}$$

C
$$17.2$$ x $$10^{-3}$$ $$s^{-1}$$

D
$$1.8$$ x $$10^{-5}$$ $$s^{-1}$$

Solution

$$k=\dfrac{2.303}{t}log\dfrac{[R_o]}{[R_t]}$$

$$\Rightarrow k=\dfrac{2.303}{1.38\times 3600}log\dfrac{[R_o]}{[0.25R_o]}$$

$$\Rightarrow k=2.8\times10^{-4}\ s^{-1}$$
Question 5
1 / -0

The rate of reaction increases with rise in temperature because of :

A
increase in the number of activated molecules

B
increase in the activation energy

C
decrease in the activation energy

D
increase in the number of molecular collisions

Solution

As the temperature is increased, the molecules acquire speed and start moving at a faster rate.

This increases the number of collisions between the molecules, thus decreasing the activation energy and increasing the rate of the reaction.

Therefore, the option is C.
Question 6
1 / -0

Wrong data for the first order reaction is:

A
$${ t }_{ 0.5 }=100s, { t }_{ 0.75 }=200s$$

B
$${ t }_{ 0.75 }=32 min,\ { t }_{ 0.5 }=16 min$$

C
both the above

D
$${ t }_{ 0.5 }=100s, { t }_{ 0.5 }=150s$$

Solution

In a 1st Order Reaction,

$${t}_{0.75} = 2\times {t}_{0.5}$$

So, Option A and B are correct

Option D is wrong.
Question 7
1 / -0

$$t_{\dfrac{1}{2}}$$ for first order reaction is:

A
$$\dfrac{0.7}{k}$$

B
$$\dfrac{0.693}{k}$$

C
$$\dfrac{0.683}{k}$$

D
$$\dfrac{0.10}{k}$$

Solution

We know, for first order reaction,
$$t_{1/2} = \dfrac{0.693}{k}$$

Hence, option B is correct.
Question 8
1 / -0

Why do most chemical reaction rates increase rapidly as the temperature rises

A
The fraction of molecular with kinetic energy grater than the activation energy increases rapidly with temperature

B
The average kinetic increases as temperature rises

C
The activation energy decreases as temperature rise

D
More collisions take place between particle so that the reaction can occur

Solution

As the temperature rises, more collisions start taking place which results in an increase in rate of the chemical reaction.
Hence, option D is correct.
Question 9
1 / -0

The activation energy for the bimolecular reaction $$A+BC \rightarrow AB+C$$ is $$E_{0}$$ in the gas phase. If the reason carried out in a confined volume of $$\lambda^{3}$$, the activation energy is expected to:

A
remain unchanged

B
increase with decreasing $$\lambda$$.

C
decrease with decreasing $$\lambda$$.

D
oscillate with decreasing $$\lambda$$.

Solution

The minimum energy requirement that must be met for a chemical reaction to occur is called the activation energy. The activation energy depends on nature of the reacting species or reactants. It does not depends on volume that is it will remain constant irrespective of the volume.
So, (A) remain unchanged -- is the correct option
Question 10
1 / -0

Radioactive decay follows order kinetics

A
0

B
1

C
2

D
3

Solution

Radioactive decay follows first order kinetics. Hence, option B is correct.

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Chemical Kinetics Test - 17

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Chemical Kinetics Test - 17

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Question 1

First order unimolecular

Second order unimolecular

Second order bimolecular

First order bimolecular

Solution

Question 2

$$kt=\cfrac{[A]}{[A]_o}$$

$$kt=[A]-[A]_o$$

$$[A]=-kt+[A]_o$$

$$[A]=kt-[A]_o$$

Solution

Question 3

25 %

50%

75%

90%

Solution

Question 4

$$3.6$$ x $$10^{-3}$$ $$s^{-1}$$

$$2.8$$ x $$10^{-4}$$ $$s^{-1}$$

$$17.2$$ x $$10^{-3}$$ $$s^{-1}$$

$$1.8$$ x $$10^{-5}$$ $$s^{-1}$$

Solution

Question 5

increase in the number of activated molecules

increase in the activation energy

decrease in the activation energy

increase in the number of molecular collisions

Solution

Question 6

$${ t }_{ 0.5 }=100s, { t }_{ 0.75 }=200s$$

$${ t }_{ 0.75 }=32 min,\ { t }_{ 0.5 }=16 min$$

both the above

$${ t }_{ 0.5 }=100s, { t }_{ 0.5 }=150s$$

Solution

Question 7

$$\dfrac{0.7}{k}$$

$$\dfrac{0.693}{k}$$

$$\dfrac{0.683}{k}$$

$$\dfrac{0.10}{k}$$

Solution

Question 8

The fraction of molecular with kinetic energy grater than the activation energy increases rapidly with temperature

The average kinetic increases as temperature rises

The activation energy decreases as temperature rise

More collisions take place between particle so that the reaction can occur

Solution

Question 9

remain unchanged

increase with decreasing $$\lambda$$.

decrease with decreasing $$\lambda$$.

oscillate with decreasing $$\lambda$$.

Solution

Question 10

0

1

2

3

Solution

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