61.
In the Arrhenius plot of $$\ln \,k\,Vs\frac{1}{T},$$ a linear plot is obtained with a slope of $$ - 2 \times {10^4}K.$$ The energy of activation of the reaction $$\left( {{\text{in}}\,kJ\,mol{e^{ - 1}}} \right)$$ is ( $$R$$ value is $$8.3\,J\,{K^{ - 1}}\,mo{l^{ - 1}})$$
62.
For the reaction, $${N_2} + 3{H_2} \to 2N{H_3},$$ if $$\frac{{d\left[ {N{H_3}} \right]}}{{dt}} = 2 \times {10^{ - 4}}mol\,{L^{ - 1}}{s^{ - 1}},$$ the value of $$\frac{{ - d\left[ {{H_2}} \right]}}{{dt}}$$ would be
A
$$3 \times {10^{ - 4}}mol\,{L^{ - 1}}{s^{ - 1}}$$
B
$$4 \times {10^{ - 4}}mol\,{L^{ - 1}}{s^{ - 1}}$$
C
$$6 \times {10^{ - 4}}mol\,{L^{ - 1}}{s^{ - 1}}$$
D
$$1 \times {10^{ - 4}}mol\,{L^{ - 1}}{s^{ - 1}}$$
64.
At $${518^ \circ }C,$$ the rate of decomposition of a sample of gaseous acetaldehyde, initially at a pressure of $$363\,Torr,$$ was $$1.00\,Torr\,{S^{ - 1}}$$ when $$5\% $$ had reacted and $$0.5\,Torr\,{S^{ - 1}}$$ when $$33\% $$ had reacted. The order of the reaction is :
According to Arrhenius equation,
$$k = A.{e^{ - \,\frac{{{E_a}}}{{RT}}}}$$
where $$k = $$ rate constant
or $$\ell n\,k = \ell n\,A - \frac{{{E_a}}}{{RT}}$$
$$A =$$ frequency factor
$${E_a} = $$ Energy of activation.
66.
In a reaction, $$2HI \to {H_2} + {I_2},$$ the concentration of $$HI$$ decreases from $$0.5\,mol\,{L^{ - 1}}$$ to $$0.4\,mol\,{L^{ - 1}}$$ in 10 minutes. What is the rate of reaction during this interval?
NOTE : Order is the sum of the power of the concentrations terms in rate law expression.
Hence the order of reaction is = 1 + 2 = 3
68.
The rate of reaction between two reactants $$A$$ and $$B$$ decreases by a factor of 4, if the concentration of reactant $$B$$ is doubled. The order of this reaction with respect to reactant $$B$$ is
$$\eqalign{
& A + B \to {\text{Product}} \cr
& {\text{Rate,}}\,\,r \propto {\left[ A \right]^x}{\left[ B \right]^y}\,\,\,...{\text{(i)}} \cr} $$
The rate decreases by a factor 4 if the concentration of reactant $$B$$ is doubled
$$\eqalign{
& \frac{r}{4} \propto {\left[ A \right]^x}{\left[ {2B} \right]^y}\,\,\,...{\text{(ii)}} \cr
& {\text{From Eqs}}{\text{. (i) and (ii}}) \cr
& 4 = {\left( {\frac{1}{2}} \right)^y} \cr
& y = - 2 \cr} $$
Hence, order of reaction with respect to $$B$$ is $$-2.$$
69.
What will be the half-life of the first order reaction for which the value of rate constant is $$200\,{s^{ - 1}}?$$
70.
In the reaction, $$A + 2B \to 6C + 2D,$$ If the initial rate $$ - \frac{{d\left[ A \right]}}{{dt}}$$ at $$t=0$$ is $$2.6 \times {10^{ - 2}}M\,{\sec ^{ - 1}},$$ what will be the value of $$\frac{{d\left[ B \right]}}{{dt}}$$ at $$t = 0?$$