Chemistry Crash Course NEET>Chapter 10 - Chemical Kinetics>Level 2>Q 11

MEDIUM

NEET

IMPORTANT

Earn 100

Two substances $A$ and $B$ are present such that $[A] = 4 [B]$ . The half-life of $A$ is $5$ minutes and of $B$ is $15$ minutes. If they start decaying at the same time, following first-order kinetics, after how much time will the concentration of both become equal?

54.55% studentsanswered this correctly

Important Questions on Chemical Kinetics

MEDIUM

NEET

IMPORTANT

Chemistry Crash Course NEET>Chapter 10 - Chemical Kinetics>Level 2>Q 12

The age of a bottle of wine is determined by monitoring the tritium levels in the wine. The activity of tritium is determined to be decreased by

8.0 %

that of a sample of fresh grape juice from the same region from which the wine was bottled. How old is the wine?

(t_{1 / 2}

of tritium is

12.3

years).

MEDIUM

NEET

IMPORTANT

Chemistry Crash Course NEET>Chapter 10 - Chemical Kinetics>Level 2>Q 13

For a first-order reaction, $3 A \to 2 B,$ the concentration of $A$ and $B$ at the point of intersection is given in the figure:

Question Image

If $A_{0} = 20$ mol $mol L^{- 1}, [B]$ at the time $t$ is equal to:

MEDIUM

NEET

IMPORTANT

Chemistry Crash Course NEET>Chapter 10 - Chemical Kinetics>Level 2>Q 14

The half-life for the radioactive decay of

{}^{14}C

is 5730 years. An archaeological artefact containing wood had only

25 %

of the

{}^{14}C

found in a living tree. The approximate age of the sample is

MEDIUM

NEET

IMPORTANT

Chemistry Crash Course NEET>Chapter 10 - Chemical Kinetics>Level 2>Q 15

The time taken for

99.9 %

of a first order reaction to complete is

7 \frac{1}{2} hrs .

The natural half-life of this reaction is nearly

MEDIUM

NEET

IMPORTANT

Chemistry Crash Course NEET>Chapter 10 - Chemical Kinetics>Level 2>Q 16

A radioactive substance decays

20 %

in

10 minutes

. If in the beginning, there are

5 \times 10^{20}

atoms present, after what time will the number of atoms be reduced to

10^{18}

atoms?

MEDIUM

NEET

IMPORTANT

Chemistry Crash Course NEET>Chapter 10 - Chemical Kinetics>Level 2>Q 17

For the first-order reaction,

C_{2} H_{4} O_{(g)} \to {CH}_{4 (g)} + {CO}_{(g)}

, the initial pressure of

C_{2} H_{4} O (g)

is

80

torr and the total pressure at the end of

20

minutes is

120

torr. The time needed for

75 %

decomposition of

C_{2} H_{4} O

would be:

MEDIUM

NEET

IMPORTANT

Chemistry Crash Course NEET>Chapter 10 - Chemical Kinetics>Level 2>Q 18

The decomposition of a substance

{}^{'}R^{'}

takes place according to first-order kinetics. Its initial concentration is reduced to

1 / 8^{th}

in

24 seconds

. The rate constant of the reaction is:

MEDIUM

NEET

IMPORTANT

Chemistry Crash Course NEET>Chapter 10 - Chemical Kinetics>Level 2>Q 19

If a first-order reaction completes to

z %

in

20

minutes and to

19 %

in

40

minutes, then the value of

z

is