(C) For a first order reaction,the half-life is given by $t_{1/2} = \frac{0.693}{k}$. This expression shows that $t_{1/2}$ is independent of the initi

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Assertion is true but Reason is false.

(C) For a first order reaction,the half-life is given by $t_{1/2} = \frac{0.693}{k}$. This expression shows that $t_{1/2}$ is independent of the initial concentration $[R]_0$. Therefore,the Assertion is true. For a first order reaction,the rate law is $Rate = k[R]^1$. The rate constant $k$ is a constant at a given temperature and is independent of the concentration of the reactant $[R]$. Therefore,the Reason is false.

Class 12 Chemistry Chemical Kinetics First Order reaction

Medium

Assertion : For a first order reaction,$t_{1/2}$ is independent of initial concentration.
Reason : For a first order reaction,rate constant $k \propto [R]$.

A
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B
Both Assertion and Reason are true but Reason is $\text{NOT}$ the correct explanation of Assertion.
C
Assertion is true but Reason is false.
D
Assertion is false but Reason is true.

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Chemical Kinetics

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First Order reaction

Derive the equation showing the relation between the concentration $[R]_1$ and $[R]_2$ at time $t_1$ and $t_2$ for a first-order reaction.

Difficult

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Which one of the following plots is correct for a first order reaction?

MediumTS EAMCET 2013

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The thermal decomposition of a molecule follows a first-order reaction. The molecule decomposes $50\%$ in $120 \text{ minutes}$. How many minutes will it take for $90\%$ decomposition?

Difficult

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For a first-order reaction,the time taken for the initial concentration to decrease to $1/4$ of its value is $20 \ min$. The time taken for the initial concentration to decrease to $1/16$ of its value will be $......... \ min$.

Medium

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$A$ reaction which is of first order with respect to reactant $A$,has a rate constant $6 \, min^{-1}$. If we start with $[A] = 0.5 \, mol \, L^{-1}$,when would $[A]$ reach the value of $0.05 \, mol \, L^{-1}$?

MediumAIIMS 2013

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Assertion : For a first order reaction,$t_{1/2}$ is independent of initial concentration. Reason : For a first order reaction,rate constant $k \propto [R]$.

Similar Questions

Derive the equation showing the relation between the concentration $[R]_1$ and $[R]_2$ at time $t_1$ and $t_2$ for a first-order reaction.

Which one of the following plots is correct for a first order reaction?

The thermal decomposition of a molecule follows a first-order reaction. The molecule decomposes $50\%$ in $120 \text{ minutes}$. How many minutes will it take for $90\%$ decomposition?

For a first-order reaction,the time taken for the initial concentration to decrease to $1/4$ of its value is $20 \ min$. The time taken for the initial concentration to decrease to $1/16$ of its value will be $......... \ min$.

$A$ reaction which is of first order with respect to reactant $A$,has a rate constant $6 \, min^{-1}$. If we start with $[A] = 0.5 \, mol \, L^{-1}$,when would $[A]$ reach the value of $0.05 \, mol \, L^{-1}$?

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Assertion : For a first order reaction,$t_{1/2}$ is independent of initial concentration.
Reason : For a first order reaction,rate constant $k \propto [R]$.