Exercise-3

The rate constant for the reaction $2{ \mathrm{N}}_2{\mathrm{O}}_5⟶4{\mathrm{NO}}_2+{\mathrm{O}}_2,$ is $3\times {10}^{-5}{ \mathrm{s}}^{-1}.$ If the rate is $2.4\times {10}^{-5}$ ${\mathrm{molL}}^{-1}{ \mathrm{s}}^{-1},$ then the concentration of ${\mathrm{N}}_2{\mathrm{O}}_5$ (in ${\mathrm{molL}}^{-1}$) is:

In the biologically -catalysed oxidation of ethanol, the concentration of ethanol decreases in a first order reaction from $800 {\mathrm{moldm}}^{-3}$ to $50 {\mathrm{moldm}}^{-3}$ in $2\times {10}^4 \mathrm{s}.$ The constant rate$\left({\mathrm{s}}^{-1}\right)$ of the reaction is:

Plots showing the variation of the rate constant $\left(\mathrm{k}\right)$ with temperature $\left(\mathrm{T}\right)$ are given below. The plot that follows Arrhenius equation is:

In the reaction, $\mathrm{P}+\mathrm{Q}⟶\mathrm{R}+\mathrm{S}$
the time taken for $75\%$ reaction of $\mathrm{P}$ , is twice the time taken for $50\%$ reaction of $\mathrm{P}.$ The concentration of $\mathrm{Q}$ varies with reaction time as shown in the figure. The overall order of the reaction is:

For the reaction, $3\mathrm{A}+2\mathrm{B}\to \mathrm{C}+\mathrm{D},$ the differential rate law can be written as:

The reaction of ozone with oxygen atoms in the presence of chlorine atoms can occur by a two-step process shown below:

${\mathrm{O}}_3 \left(\mathrm{g}\right)+\mathrm{Cl}° \left(\mathrm{g}\right)\to {\mathrm{O}}_{2 }\left(\mathrm{g}\right)+\mathrm{ClO}° \left(\mathrm{g}\right) ...\left(\mathrm{i}\right)$

${\mathrm{k}}_{\mathrm{i}}=5.2\times {10}^9\mathrm{L} {\mathrm{mol}}^{-1}{\mathrm{s}}^{-1}$

$\mathrm{ClO}° \left(\mathrm{g}\right)+\mathrm{O}° \left(\mathrm{g}\right)\to {\mathrm{O}}_{2 }\left(\mathrm{g}\right)+\mathrm{Cl}° \left(\mathrm{g}\right) ...\left(\mathrm{ii}\right)$

${\mathrm{k}}_{\mathrm{i}}=2.6\times {10}^{10}\mathrm{L} {\mathrm{mol}}^{-1}{\mathrm{s}}^{-1}$

The closest rate constant for the overall reaction ${\mathrm{O}}_{3 }\left(\mathrm{g}\right)+\mathrm{O}° \left(\mathrm{g}\right)\to 2{\mathrm{O}}_{2 }\left(\mathrm{g}\right)$ is:

For an elementary chemical reaction,

${\mathrm{A}}_2\underset{{\mathrm{K}}_{-1}}{\overset{{\mathrm{K}}_1}{\rightleftharpoons }}2\mathrm{A}$ the expressions for $\frac{\mathrm{d}\left[\mathrm{A}\right]}{\mathrm{dt}}$

The half life of a radio isotope is four hours. If the initial mass of the isotope was 200 g, the mass remaining after 24 hours undecayed is