Problem 59
For a first order homogeneous gaseous reaction, \(A \longrightarrow 2 B+C\) then initial pressure was \(P_{i}\) while total pressure after time ' \(t\) ' was \(P_{t}\). The right expression for the rate constants \(k\) in terms of \(P_{i}, P_{t}\) and \(t\) is : (a) \(k=\frac{2.303}{t} \log \left(\frac{2 P_{i}}{3 P_{i}-P_{t}}\right)\) (b) \(k=\frac{2.303}{t} \log \left(\frac{2 P_{i}}{2 P_{t}-P_{i}}\right)\) (c) \(k=\frac{2.303}{t} \log \left(\frac{P_{i}}{P_{i}-P_{t}}\right)\) (d) none of these
Problem 60
The decomposition of azo methane, at certain temperature according to the equation \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{~N}_{2} \longrightarrow \mathrm{C}_{2} \mathrm{H}_{6}+\mathrm{N}_{2}\) is a first order reaction. After 40 minutes from the start, the total pressure developed is found to be \(350 \mathrm{~mm} \mathrm{Hg}\) in place of initial pressure \(200 \mathrm{~mm} \mathrm{Hg}\) of azo methane. The value of rate constant \(k\) is : (a) \(2.88 \times 10^{-4} \mathrm{sec}^{-1}\) (b) \(1.25 \times 10^{-4} \mathrm{sec}^{-1}\) (c) \(5.77 \times 10^{-4} \mathrm{sec}^{-1}\) (d) None of these
Problem 61
The hydrolysis of sucrose was studied with the help of polarimeter and following data were collected time (min.) \(\begin{array}{lll}: 0 & 70 & \infty\end{array}\) observed rotation (degrees) \(\begin{array}{lll}: 44 & 16.5 & -11\end{array}\) when the reaction mixture will be optically inactive ? (Given: \(\ln 2=0.7, \ln 3=1.1, \ln 5=1.6\) ) (a) 16 min. (b) \(69.47 \mathrm{~min}\). (c) \(160 \mathrm{~min}\). (d) none of these
Problem 65
At \(300 \mathrm{~K}\) the half-life of a sample of a gaseous compound initially at \(1 . \mathrm{atm}\) is \(100 \mathrm{sec}\). When the pressure is \(0.5\) atm the half-life is \(50 \mathrm{sec}\). The order of reaction is : (a) 0 (b) 1 (c) 2 (d) 3
Problem 68
The activation energy of the reaction, \(A+B \longrightarrow C+D+38 \mathrm{kcal}\) is \(20 \mathrm{kcal}\), What would be the activation energy of the reaction, \(C+D \rightarrow A+B\) (a) \(20 \mathrm{kcal}\) (b) \(-20 \mathrm{kcal}\) (c) \(18 \mathrm{kcal}\) (d) 58 kcal
Problem 72
\(\frac{k_{35^{\circ}}}{k_{34^{\circ}}}>1\), this means that (a) Rate increases with the rise in temperature (b) Rate decreases with rise in temperature (c) rate does not change with rise in temperature (d) None of the above
Problem 73
The plot of \(\ln k\) versus \(1 / T\) is linear with slope of: (a) \(-E_{a} / R\) (b) \(E_{a} / R\) (c) \(E_{a} / 2.303 R\) (d) \(-E_{a} / 2.303 R\)
Problem 77
The activation energies of the forward and backward reactions in the case of a chemical reaction are \(30.5\) and \(45.4 \mathrm{~kJ} / \mathrm{mol}\) respectively. The reaction is : (a) Exothermic (b) Endothermic (c) Neither exothermic nor endothermic (d) Independent of temperature
Problem 79
The temperature coefficient of a reaction is : (a) The rate constant (b) The rate constant at a fixed temperature (c) The ratio of rate constant at two temperature (d) The ratio of rate constant differing by \(10^{\circ} \mathrm{C}\) preferably \(k_{308} / k_{298}\)
Problem 82
A first order reaction is \(50 \%\) completed in 20 minutes at \(27^{\circ} \mathrm{C}\) and in 5 minutes at \(47^{\circ} \mathrm{C}\). The energy of activation of the reaction is : (a) \(43.85 \mathrm{~kJ} / \mathrm{mol}\) (b) \(55.14 \mathrm{~kJ} / \mathrm{mol}\) (c) \(11.97 \mathrm{~kJ} / \mathrm{mol}\) (d) \(6.65 \mathrm{~kJ} / \mathrm{mol}\)
