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CHXII04:CHEMICAL KINETICS

320531 Match the following columns and choose the correct option from the codes given below.
Column I
Column II
A
Unimolecular
P
$2 H I \to H_{2} + I_{2}$
B
Bimolecular
Q
$2 N O + O_{2} \to 2 N O_{2}$
C
Trimolecular
R
$N H_{4} N O_{2} \to N_{2} + 2 H_{2} O$

1 A - Q, B - P, C - R

2 A - Q, B - R, C - P

3 A - R, B - P, C - Q

4 A - R, B - Q, C - P

MHTCET - 2018

CHXII04:CHEMICAL KINETICS

320532 Mechanism of a hypothetical reaction
$X_{2} + Y_{2} \to 2 XY is given below :$
(i) $X_{2} ⇌ X + X$ (fast)

(ii) $X + Y_{2} \to XY + Y$ (slow)
(iii) $X + Y \to XY$ (fast)
The overall order of the reaction will be :

1 2

2 0

3 1.5

4 1

Explanation:

From slow step i.e., rds,
$r = k [X] [Y_{2}]$
from fast step (i)
$\begin{aligned} K_{eq} = \frac{[X]^{2}}{[X_{2}]} \\ [X]^{2} = K_{eq} \cdot [X_{2}] \\ [X] = \sqrt{K_{eq}} {[X_{2}]}^{1 / 2} \end{aligned}$
From equation (1) \& (2)
$\begin{aligned} r = k \cdot \sqrt{K_{eq}} {[X_{2}]}^{1 / 2} [Y_{2}] \\ r = k^{'} {[X_{2}]}^{1 / 2} [Y_{2}] . \end{aligned}$
Overall order of reaction $= 1 + 0.5 = 1.5$

NEET - 2017

CHXII04:CHEMICAL KINETICS

320533 The following mechanism proposed for $NOBr$ : $NO + {Br}_{2} ⇌ {NOBr}_{2}$ (fast)

${NOBr}_{2} + NO \to 2 NOBr$ (slow)

The order of reaction w.r.t. to $NO$ is

1 1

2 2

3 0

4

1 / 2

Explanation:

Rate law from slowest step is,
$r = k [N O B r_{2}] [N O] (1)$
$From, NO + B r_{2} ⇌ NOB r_{2}$
$K = \frac{[N O B r_{2}]}{[N O] [B r_{2}]}$
$[N O B r_{2}] = K [N O] [B r_{2}]$
$S u b s t i t u t e i n e q u a t i o n (1)$
$r = k \cdot K \cdot [N O] [B r_{2}] [N O]$
${\rm{r = }}{{\rm{k}}^{\rm{1}}}{\mkern 1mu} {[{\rm{NO}}]^{\rm{2}}}{[{\rm{B}}{{\rm{r}}_{\rm{2}}}]^{\rm{1}}}$
$∴ O r d e r w . r . t N O = 2$

CHXII04:CHEMICAL KINETICS

320534 Assertion :
In $A \overset{k_{1}}{\to} B \overset{k_{2}}{\to} C$ If half-life of A is very less as compared to B, so the net reaction is $A \to C$ with rate constant $(k_{1} \times k_{2})$
Reason :
Slowest step is the rate determining step so $B \to C$ is rate determining step.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

CHXII04:CHEMICAL KINETICS

320531 Match the following columns and choose the correct option from the codes given below.
Column I
Column II
A
Unimolecular
P
$2 H I \to H_{2} + I_{2}$
B
Bimolecular
Q
$2 N O + O_{2} \to 2 N O_{2}$
C
Trimolecular
R
$N H_{4} N O_{2} \to N_{2} + 2 H_{2} O$

1 A - Q, B - P, C - R

2 A - Q, B - R, C - P

3 A - R, B - P, C - Q

4 A - R, B - Q, C - P

MHTCET - 2018

CHXII04:CHEMICAL KINETICS

320532 Mechanism of a hypothetical reaction
$X_{2} + Y_{2} \to 2 XY is given below :$
(i) $X_{2} ⇌ X + X$ (fast)

(ii) $X + Y_{2} \to XY + Y$ (slow)
(iii) $X + Y \to XY$ (fast)
The overall order of the reaction will be :

1 2

2 0

3 1.5

4 1

Explanation:

From slow step i.e., rds,
$r = k [X] [Y_{2}]$
from fast step (i)
$\begin{aligned} K_{eq} = \frac{[X]^{2}}{[X_{2}]} \\ [X]^{2} = K_{eq} \cdot [X_{2}] \\ [X] = \sqrt{K_{eq}} {[X_{2}]}^{1 / 2} \end{aligned}$
From equation (1) \& (2)
$\begin{aligned} r = k \cdot \sqrt{K_{eq}} {[X_{2}]}^{1 / 2} [Y_{2}] \\ r = k^{'} {[X_{2}]}^{1 / 2} [Y_{2}] . \end{aligned}$
Overall order of reaction $= 1 + 0.5 = 1.5$

NEET - 2017

CHXII04:CHEMICAL KINETICS

320533 The following mechanism proposed for $NOBr$ : $NO + {Br}_{2} ⇌ {NOBr}_{2}$ (fast)

${NOBr}_{2} + NO \to 2 NOBr$ (slow)

The order of reaction w.r.t. to $NO$ is

1 1

2 2

3 0

4

1 / 2

Explanation:

Rate law from slowest step is,
$r = k [N O B r_{2}] [N O] (1)$
$From, NO + B r_{2} ⇌ NOB r_{2}$
$K = \frac{[N O B r_{2}]}{[N O] [B r_{2}]}$
$[N O B r_{2}] = K [N O] [B r_{2}]$
$S u b s t i t u t e i n e q u a t i o n (1)$
$r = k \cdot K \cdot [N O] [B r_{2}] [N O]$
${\rm{r = }}{{\rm{k}}^{\rm{1}}}{\mkern 1mu} {[{\rm{NO}}]^{\rm{2}}}{[{\rm{B}}{{\rm{r}}_{\rm{2}}}]^{\rm{1}}}$
$∴ O r d e r w . r . t N O = 2$

CHXII04:CHEMICAL KINETICS

320534 Assertion :
In $A \overset{k_{1}}{\to} B \overset{k_{2}}{\to} C$ If half-life of A is very less as compared to B, so the net reaction is $A \to C$ with rate constant $(k_{1} \times k_{2})$
Reason :
Slowest step is the rate determining step so $B \to C$ is rate determining step.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

CHXII04:CHEMICAL KINETICS

320531 Match the following columns and choose the correct option from the codes given below.
Column I
Column II
A
Unimolecular
P
$2 H I \to H_{2} + I_{2}$
B
Bimolecular
Q
$2 N O + O_{2} \to 2 N O_{2}$
C
Trimolecular
R
$N H_{4} N O_{2} \to N_{2} + 2 H_{2} O$

1 A - Q, B - P, C - R

2 A - Q, B - R, C - P

3 A - R, B - P, C - Q

4 A - R, B - Q, C - P

MHTCET - 2018

CHXII04:CHEMICAL KINETICS

320532 Mechanism of a hypothetical reaction
$X_{2} + Y_{2} \to 2 XY is given below :$
(i) $X_{2} ⇌ X + X$ (fast)

(ii) $X + Y_{2} \to XY + Y$ (slow)
(iii) $X + Y \to XY$ (fast)
The overall order of the reaction will be :

1 2

2 0

3 1.5

4 1

Explanation:

From slow step i.e., rds,
$r = k [X] [Y_{2}]$
from fast step (i)
$\begin{aligned} K_{eq} = \frac{[X]^{2}}{[X_{2}]} \\ [X]^{2} = K_{eq} \cdot [X_{2}] \\ [X] = \sqrt{K_{eq}} {[X_{2}]}^{1 / 2} \end{aligned}$
From equation (1) \& (2)
$\begin{aligned} r = k \cdot \sqrt{K_{eq}} {[X_{2}]}^{1 / 2} [Y_{2}] \\ r = k^{'} {[X_{2}]}^{1 / 2} [Y_{2}] . \end{aligned}$
Overall order of reaction $= 1 + 0.5 = 1.5$

NEET - 2017

CHXII04:CHEMICAL KINETICS

320533 The following mechanism proposed for $NOBr$ : $NO + {Br}_{2} ⇌ {NOBr}_{2}$ (fast)

${NOBr}_{2} + NO \to 2 NOBr$ (slow)

The order of reaction w.r.t. to $NO$ is

1 1

2 2

3 0

4

1 / 2

Explanation:

Rate law from slowest step is,
$r = k [N O B r_{2}] [N O] (1)$
$From, NO + B r_{2} ⇌ NOB r_{2}$
$K = \frac{[N O B r_{2}]}{[N O] [B r_{2}]}$
$[N O B r_{2}] = K [N O] [B r_{2}]$
$S u b s t i t u t e i n e q u a t i o n (1)$
$r = k \cdot K \cdot [N O] [B r_{2}] [N O]$
${\rm{r = }}{{\rm{k}}^{\rm{1}}}{\mkern 1mu} {[{\rm{NO}}]^{\rm{2}}}{[{\rm{B}}{{\rm{r}}_{\rm{2}}}]^{\rm{1}}}$
$∴ O r d e r w . r . t N O = 2$

CHXII04:CHEMICAL KINETICS

320534 Assertion :
In $A \overset{k_{1}}{\to} B \overset{k_{2}}{\to} C$ If half-life of A is very less as compared to B, so the net reaction is $A \to C$ with rate constant $(k_{1} \times k_{2})$
Reason :
Slowest step is the rate determining step so $B \to C$ is rate determining step.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

CHXII04:CHEMICAL KINETICS

320531 Match the following columns and choose the correct option from the codes given below.
Column I
Column II
A
Unimolecular
P
$2 H I \to H_{2} + I_{2}$
B
Bimolecular
Q
$2 N O + O_{2} \to 2 N O_{2}$
C
Trimolecular
R
$N H_{4} N O_{2} \to N_{2} + 2 H_{2} O$

1 A - Q, B - P, C - R

2 A - Q, B - R, C - P

3 A - R, B - P, C - Q

4 A - R, B - Q, C - P

MHTCET - 2018

CHXII04:CHEMICAL KINETICS

320532 Mechanism of a hypothetical reaction
$X_{2} + Y_{2} \to 2 XY is given below :$
(i) $X_{2} ⇌ X + X$ (fast)

(ii) $X + Y_{2} \to XY + Y$ (slow)
(iii) $X + Y \to XY$ (fast)
The overall order of the reaction will be :

1 2

2 0

3 1.5

4 1

Explanation:

From slow step i.e., rds,
$r = k [X] [Y_{2}]$
from fast step (i)
$\begin{aligned} K_{eq} = \frac{[X]^{2}}{[X_{2}]} \\ [X]^{2} = K_{eq} \cdot [X_{2}] \\ [X] = \sqrt{K_{eq}} {[X_{2}]}^{1 / 2} \end{aligned}$
From equation (1) \& (2)
$\begin{aligned} r = k \cdot \sqrt{K_{eq}} {[X_{2}]}^{1 / 2} [Y_{2}] \\ r = k^{'} {[X_{2}]}^{1 / 2} [Y_{2}] . \end{aligned}$
Overall order of reaction $= 1 + 0.5 = 1.5$

NEET - 2017

CHXII04:CHEMICAL KINETICS

320533 The following mechanism proposed for $NOBr$ : $NO + {Br}_{2} ⇌ {NOBr}_{2}$ (fast)

${NOBr}_{2} + NO \to 2 NOBr$ (slow)

The order of reaction w.r.t. to $NO$ is

1 1

2 2

3 0

4

1 / 2

Explanation:

Rate law from slowest step is,
$r = k [N O B r_{2}] [N O] (1)$
$From, NO + B r_{2} ⇌ NOB r_{2}$
$K = \frac{[N O B r_{2}]}{[N O] [B r_{2}]}$
$[N O B r_{2}] = K [N O] [B r_{2}]$
$S u b s t i t u t e i n e q u a t i o n (1)$
$r = k \cdot K \cdot [N O] [B r_{2}] [N O]$
${\rm{r = }}{{\rm{k}}^{\rm{1}}}{\mkern 1mu} {[{\rm{NO}}]^{\rm{2}}}{[{\rm{B}}{{\rm{r}}_{\rm{2}}}]^{\rm{1}}}$
$∴ O r d e r w . r . t N O = 2$

CHXII04:CHEMICAL KINETICS

320534 Assertion :
In $A \overset{k_{1}}{\to} B \overset{k_{2}}{\to} C$ If half-life of A is very less as compared to B, so the net reaction is $A \to C$ with rate constant $(k_{1} \times k_{2})$
Reason :
Slowest step is the rate determining step so $B \to C$ is rate determining step.

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but reason is correct.

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