HARD

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 1

The rate of a reaction escalates four times when the temperature changes from $300 K$ to $320 K .$ Determine the energy of activation of the reaction, assuming that it does not change with temperature? $(R = 8 .314 J K^{- 1} {mol}^{- 1})$

HARD

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 2

The activation energy for the reaction $2 HI (g) \to H_{2} (g) + I_{2} (g)$ is $209 .5 {kJmol}^{- 1}$ at $581 K$ . The fraction of molecules having energy equal to or greater than activation energy is: $[R = 8 .31 {JK}^{- 1} {mol}^{- 1}]$

HARD

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 3

In a pseudo first order hydrolysis of ester in water, the following results are obtained:

$t$ in seconds	$0$	$30$	$60$	$90$
$[Ester] M$	$0.55$	$0.31$	$0.17$	$0.085$

(i) The average rate of reaction between the time interval 30 to 60 seconds and

(ii) The pseudo first order rate constant for the hydrolysis of ester is?

HARD

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 4

For a decomposition reaction the values of rate constant k at two different temperatures are given below :

$\begin{array}{l} k_{1} = 2.15 \times 10^{- 8} L m o l^{- 1} s^{- 1} a t 650 K \\ k_{2} = 2.39 \times 10^{- 7} L m o l^{- 1} s^{- 1} a t 700 K \end{array}$

The value of activation energy for this reaction is:

$(R = 8.314 J K^{- 1} m o l^{- 1})$

HARD

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 5

A first order reaction is $20 %$ complete in $5$ minute. Calculate the time taken for the reaction to be $60 %$ complete:

$\log 2.5 = 0.3979$ , $\log 1.25 = 0.0969$

MEDIUM

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 6

The half-life for decay of radioactive ${}^{14}C$ is 5730 years. An archaeological artifact containing wood has only 80% of the ${}^{14}C$ activity as found in living trees. The age of the artifact would be:
[Given: log 1.25 = 0.0969]

HARD

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 7

$A + 2 B \underset{}{\to} 3 C + 2 D .$

The ratio of disappearance of B is $1 \times 10^{- 2} m o l / L / S .$ The rate of reaction and rate of change in concentration of A and C would be:

EASY

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 8

For a hypothetical reaction $A \to B$ , the activation energy for forward and backward reactions are $19 kJ / mol$ and $9 kJ / mol$ respectively. The heat of reaction is

MEDIUM

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 9

In a first-order reaction, the concentration of reactant decreases from $800 {mol/dm}^{3} {to 50 mol/dm}^{3}$ in $2 \times 10^{2} s$ . The rate constant of reaction in $s^{- 1}$ is

MEDIUM

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 10

Consider a reaction $a G + bH \to products$ . When concentration of both the reactants G and H is doubled, the rate increases by eight times. However, when concentration of G is doubled keeping the concentration of H constant, the rate is doubled. The overall order of the reaction is:

MEDIUM

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 11

Consider a reaction $a G + bH \to products$ . When concentration of both the reactants $G$ and $H$ is doubled, the rate increases by eight times. However, when the concentration of $G$ is doubled, keeping the concentration of $H$ constant, the rate is doubled. The overall order of the reaction is:

MEDIUM

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 12

Consider the chemical reaction:

$N_{2} (g) + 3 H_{2} (g) ⟶ 2 {NH}_{3} (g)$

The rate of this reaction can be expressed in terms of time derivatives of concentration of $N_{2} (g), H_{2} (g) and {NH}_{3} (g)$ Identify the correct relationship amongst the rate expressions:

MEDIUM

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 13

The quantitative estimation of change in the rate of reaction with change in concentration does not always follow stoichiometric equation. Justify.

EASY

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 14

For a reaction $A \to B, ∆ C_{B}$ is $0.01 mol / L$ in $20 s$ , what is the average rate of reaction?

EASY

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 15

If $K_{c}$ for the formation of $HI$ from $H_{2}$ and $I_{2}$ is $48$ , then $K_{c}$ for decomposition of $1$ mole of $HI$ is _____.

$A = 0.144 B = 1.144 C = 0.014$

Enter your correct answe as A, B or C.

EASY

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 16

In the reaction $A + B \to C, r = k [A]$ , if $[A]$ is increased by three times then the difference in the rate is _____ of the initial rate.

MEDIUM

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 17

From the following data $H_{2} + I_{2} \to 2 HI$

$T (K)$	$1 / {TK}^{- 1}$	$\log K$
$769$	$1.3 \times 10^{- 3}$	$2.9$
$667$	$1.5 \times 10^{- 3}$	$1.1$

Which of the following is the appropriate $E_{a}$ of the reaction?

MEDIUM

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 18

What is the order of a reaction whose rate constant is $5 x 10^{- 4} {mol}^{- 1} litre s^{- 1}$ ?

HARD

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 19

The plot of ${logk}_{f}$ versus $\frac{1}{T}$ for a reversible reaction $A (g) ⇌ P (g)$ is shown.

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Pre-exponential factors for the forward and backward reactions are $10^{15} s^{- 1}$ and $10^{11} s^{- 1}$ , respectively. If the value of $logK$ for the reaction at $500 K$ is $6$ , the value of $|{logk}_{b}|$ at $250 K$ is
$[K =$ equilibrium constant of the reaction, $k_{f} =$ rate constant of forward reaction, $K_{b} =$ rate constant of backward reaction]

MEDIUM

IMPORTANT

Physical Sciences>Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.>Chemical Reactions - Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.> Q 20

At $30 ° C$ , the half life for the decomposition of ${AB}_{2}$ is $200 s$ and is independent of the initial concentration of ${AB}_{2}$ . The time required for $80 %$ of the ${AB}_{2}$ to decompose is (Given: $\log 2 = 0.30; \log 3 = 0.48$ )

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