Chapter 8

The half-life periods of a reaction at initial concentrations \(0.1 \mathrm{~mol} \mathrm{~L}^{-1}\) and \(0.5 \mathrm{~mol} \mathrm{~L}^{-1}\) are \(200 \mathrm{~s}\) and \(40 \mathrm{~s}\), respectively. The order of the reaction is (a) \(\underline{1}\) (b) \(1 / 2\) (c) 2 (d) 0

Maximum number of mole of oxygen gas that can be obtained by the electrolytic decom- position of \(90 \mathrm{~g}\) of water will be $$ \begin{array}{llll}\text { pos } & \text { (c) } 5 & \text { (d) } 9\end{array} $$ (a) 1 (b) \(2.5\)

For a first order reaction, \(A \rightarrow B, t_{1 / 2}=1\) h, what fraction of the initial conc. of A reacts in \(4 \mathrm{~h}\).? (a) \(15 / 16\) (b) \(1 / 16\) (c) \(7 / 8\) (d) \(1 / 8\)

A salt bridge contains (a) A saturated solution of \(\mathrm{KCl}\) and agar-agar (b) A saturated solution of \(\mathrm{KNO}_{3}\) and agar-agar (c) A saturated solution of \(\mathrm{NH}_{4} \mathrm{NO}_{3}\) and agar-agar (d) All of these

For the reaction $$ \mathrm{Cl}_{2}(\mathrm{~g})+2 \mathrm{NO}(\mathrm{g}) \rightarrow 2 \mathrm{NOCl}(\mathrm{g}) $$ It is found that doubling the concentrations of both the reactants increases the rate by a factor of 8 . If only the concentration of \(\mathrm{Cl}_{2}^{\prime}\) is doubled, the rate increases by a factor of 2 . The order of the reaction with respect to NO is (a) \(\underline{1}\) (b) \(\overline{0}\) (c) 2 (d) \(1 / 2\)

If mercury is used as the cathode in the electrolysis of aqueous solution of \(\mathrm{NaCl}\), the ions discharged at the cathode are \(\begin{array}{llll}\text { (c) } \mathrm{Na}^{+} & \text {(d) } \mathrm{H}^{+}\end{array}\) (a) \(\mathrm{Cl}\) (b) \(\mathrm{OH}\)

The enzyme which can catalyze the conversion of glucose to ethanol is (a) Zymase (b) Invertase (c) Maltase (d) Diastase

In an electrolysis of an aqueous solution of sodium sulphate, \(2.4 \mathrm{~L}\) of oxygen at STP was liberated at anode. The volume of hydrogen at STP liberated at cathode would be (a) \(1.2 \mathrm{~L}\) (b) \(2.4 \mathrm{~L}\) (c) \(2.6 \mathrm{~L}\) (d) \(4.8 \mathrm{~L}\)

Faraday's law of electrolysis is related to the (a) atomic number of the cation (b) atomic number of the anion (c) equivalent mass of the electrolyte (d) speed of the cation

\(75 \%\) of a first-order reaction was completed in 32 min. How long did it take to complete \(50 \%\) of the reaction? (a) \(24 \mathrm{~min}\) (b) \(8 \mathrm{~min}\) (c) \(16 \mathrm{~min}\) (d) \(64 \mathrm{~min}\)

The rate of a reaction increases eight times when the concentration increases four times. 'The order of the reaction is (a) \(2.5\) (b) \(2.0\) (c) \(1.5\) (d) \(0.5\)

The increase in equivalent conductance of a weak electrolyte with dilution is due to (a) Increase in degree of dissociation and decrease in ionic mobility (b) Decrease in degree of dissociation and decrease in ionic mobility (c) Increase in degree of dissociation and increase in ionic mobility (d) Decrease in degree of dissociation and increase in ionic mobility

For a first-order reaction, the time required for \(99.9 \%\) of the reaction to take place is nearly (a) 10 times that required for half the reaction (b) 100 times that required for two-thirds of the reaction (c) 10 times that required for one-fourth of the reaction (d) 20 times that required for half of the reaction

How many faradays are required to reduce 1 mol of \(\mathrm{BrO}_{3}^{-}\)to \(\mathrm{Br}^{-}\)? (b) 5 (c) 6 (d) 4 (a) 3

The chemical reaction \(2 \mathrm{O}_{3}(\mathrm{~g}) \rightarrow 3 \mathrm{O}_{2}(\mathrm{~g})\) proceeds as follows: \(\mathrm{O}_{3} \rightleftharpoons \mathrm{O}_{2}+\mathrm{O}\) (fast) \(2 \mathrm{O}+\mathrm{O}_{2} \rightarrow 2 \mathrm{O}_{2}\) (slow) The rate law expression is (a) rate \(=k\left[\mathrm{O}_{3}\right]_{2}\) (b) rate \(=k\left[\mathrm{O}_{3}\right]^{2}\left[\mathrm{O}_{2}\right]^{-1}\) (c) rate \(=k\left[\mathrm{O}_{3}\right]\left[\mathrm{O}_{2}\right]\) (d) none of the above

In the electrolysis of alkaline water, a total of \(1 \mathrm{~mol}\) of gases is evolved. The amount of water decomposed would be (a) 1 mol (b) \(2 \mathrm{~mol}\) $$ \begin{array}{llll}\text { (c) }(1 / 3) \text { mol } & \text { (d) }(2 / 3) \mathrm{mol} & \text { mol }\end{array} $$

The half-life period of any first-order reaction (a) depends on the initial concentration of the reactant (b) does not depend on the initial concentration of the reactant (c) always depends on temperature (d) is twice the rate constant

The position of some metals in the electrochemical series in decreasing electropositive character is \(\mathrm{Mg}>\mathrm{Al}>\mathrm{Zn}>\mathrm{Cu}>\mathrm{Ag}\). What will happen if a copper spoon is used to stir a solution of aluminum nitrate. (a) The spoon gets coated with aluminium (b) An alloy of aluminium and copper is formed (c) No reaction occurs (d) The solution starts turning blue

The unit of the rate constant depends upon the (a) temperature of the reaction (b) activation energy of the reaction (c) molecularity of the reaction (d) order of the reaction

How many faradays are required to reduce \(\mathrm{Sn}^{4+}\) to \(\mathrm{Sn}^{2+} ?\) (a) \(2.0\) (b) \(4.0\) (c) \(1.0\) (d) \(6.0\)

The half-life period of reaction increases four-fold when the initial concentration is increased to four times its value. The order of the reaction is (a) 1 (b) 4 (c) 0 (d) \(\overline{2}\)

The equivalent conductances of \(\mathrm{NaCl}, \mathrm{HCl}\) and \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{COONa}\) at infinite dilution are \(126.45\), \(426.16\) and \(91 \mathrm{ohm}^{-1} \mathrm{~cm}^{2}\). The eq. conductance of \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{COOH}\) is (a) \(201.28 \mathrm{ohm}^{-1} \mathrm{~cm}^{2}\) b) \(390.71 \mathrm{ohm} \mathrm{cm}^{2}\) (c) \(698.28\) ohm \(\mathrm{cm}^{2}\) d) \(540.48 \mathrm{ohm} \mathrm{cm}^{2}\)

Chemical reactions of the type \(X \stackrel{b}{\longrightarrow}, Y \stackrel{k_{2}}{\longrightarrow} Z\) are called (a) Consecutive reactions (b) Parallel reactions (c) Reversible reaction (d) Chain reactions

During the titration of oxalic acid against \(\mathrm{KMnO}_{4}\), the autocatalyst used is (a) \(\mathrm{MnO}_{4}^{2-}\) (b) \(\mathrm{CO}_{2}\) (c) \(\mathrm{H}^{+}\) (d) \(\mathrm{Mn}^{2+}\)

Consider the cell: \(\mathrm{Cu} / \mathrm{Cu}^{2+}(0.01 \mathrm{M}) 11 \mathrm{Ag}^{+}(0.1 \mathrm{M}) \mid \mathrm{Ag}\). The e.m.f. of the cell can be increased by (a) Exchanging the concentration in the two half cells (b) Decreasing the concentrations to one tenth in each half cell (c) Making the concentrations \(1.0 \mathrm{M}\) for each side (d) Increasing the concentrations to ten times in each half cell

For a first-order reaction, the units of \(A\) in Arrhenius equation will be (a) \(\mathrm{J} \mathrm{K}^{-1} \mathrm{~s}^{-1}\) (b) \(s^{-1}\) (c) \(\mathrm{mol} \mathrm{L}^{-1} \mathrm{~s}^{-1}\) (d) \(\mathrm{J} \mathrm{K}^{-1} \mathrm{~L}^{-1} \mathrm{~s}^{-1}\)

Which of the following statements is correct for the activation energy of a reaction? (a) It increases with increase in temperature. (b) When the activation energy is zero the rate constant is temperature- dependent. (c) It decreases with decrease in temperature. (d) It is nearly independent of temperature, over a wide range.

The function of a salt bridge is to (a) eliminate liquid-junction potential where the ions are present in large excess at the junction (b) increase the cell potential at the positive electrode (c) decrease the cell potential at the negative electrode (d) eliminate the impurities present in the electrolyte

The units of specific reaction rate for a second-order reaction is (a) \(\mathrm{s}^{-1}\) (b) \(\mathrm{mol} \mathrm{L}^{-1} \mathrm{~s}^{-1}\) (c) \(\mathrm{L}^{2} \mathrm{~mol}^{-2} \mathrm{~s}^{-1}\) (d) \(\mathrm{L} \mathrm{mol}^{-1} \mathrm{~s}^{-1}\)

If the rate of the reaction is equal to the rate constant, the order of reaction is (a) 3 (b) 0 (c) 1 (d) \(\overline{2}\)

Rate of a reaction can be expressed by Arrhenius equation as, \(k=A e^{-K / R T}\), In this reaction \(E\) represents (a) The energy above which all the colliding molecules will react (b) The energy below which colliding molecules will not react

Several blocks of magnesium are fixed to the bottom of a ship to (a) Keep away the sharks (b) Make the ship lighter (c) Prevent action of water and salt (d) Prevent puncturing by under-sea rocks

Galvanization includes plating iron with (a) Zinc (b) Tin (c) Copper (d) Aluminum

A reaction involving two different reactants can never be (a) Unimolecular reaction (b) First order reaction (c) Second order reaction (d) Bimolecular reaction

Which of the following is incorrect about the order of reaction ? (a) It is calculated experimentally. (b) It is sum of powers of concentrations in rate law expression. (c) The order of reaction cannot be fractional. (d) There is not necessarily a connection between order and stochiometry of a reaction.

The highest electrical conductivity of the following aqueous solutions is of (a) \(0.1 \mathrm{M}\) fluoroacetic acid (b) \(0.1 \mathrm{M}\) difluoroacetic acid (c) \(0.1 \mathrm{M}\) acetic acid (d) 0.1 M chloroacetic acid

At infinite dilution, the aqueous solution of \(\mathrm{BaCl}_{2}\), molar conductivities of \(\mathrm{Ba}^{2+}\) and \(\mathrm{Cl}^{-}\) ions are \(127.32 \mathrm{~S} \mathrm{~cm}^{2} / \mathrm{mol}\) and \(76.34 \mathrm{~S} \mathrm{~cm}^{2} / \mathrm{mol}\) respectively. What is \(A_{\mathrm{m}}^{-}\)for \(\mathrm{BaCl}_{2}\) at same dilution ? (a) \(280 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}\) (b) \(330.98 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}\) (c) \(90.98 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}\) (d) \(203.6 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}\)

For a zero order reaction, the half life period is dependent upon (a) Initial concentration of reactants (b) Cube root of initial concentration (c) First power of final concentration (d) Square root of final concentration

In a cell that utilizes the reaction \(\mathrm{Zn}(\mathrm{s})+2 \mathrm{H}^{+}(\mathrm{aq}) \rightarrow \mathrm{Zn}^{2+}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{~g})\) addition of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) to cathode compartment will (a) Lower the \(E\) and shift equilibrium to the left (b) Increase the \(E\) and shift equilibrium to the left (c) Increase the \(E\) and shift equilibrium to the right (d) Lower the \(E\) and shift equilibrium to the right

The rate of a first order reaction is \(1.5 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~min}^{\circ}\) at \(0.5 \mathrm{x}\) reactant. The half-life of the reaction is (a) \(7.53 \mathrm{~min}\) (b) \(0.383 \mathrm{~min}\) (c) \(23.1 \mathrm{~min}\) (d) \(8.73\) min

Which of the following is the use of electrolysis? (a) Electrorefining (b) Electroplating (c) Both \(a\) and \(b\) (d) none of these

Consider the reaction, \(2 A+B \rightarrow\) Products. When concentration of \(B\) alone was doubled, ?he half life did not change. When the concentration of \(A\) alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is (a) \(\mathrm{s}^{-1}\) (b) \(\mathrm{L} \mathrm{mol}^{-1} \mathrm{~s}^{-1}\) (c) unitless (d) \(\mathrm{mol} \mathrm{L}^{-1} \mathrm{~s}^{-1}\)

On the basis of the information available for the reaction \(4 / 3 \mathrm{Al}+\mathrm{O}_{2} \rightarrow 2 / 3 \mathrm{Al}_{2} \mathrm{O}_{3}, \Delta G=-827 \mathrm{~kJ} \mathrm{~mol}^{-1}\) of the minimum e.m.f. required to carry out electrolysis of \(\mathrm{Al}_{2} \mathrm{O}_{3}\) is \(\left(F=96500 \mathrm{C} \mathrm{mol}^{-1}\right)\) (a) \(8.56 \mathrm{~V}\) (b) \(2.14 \mathrm{~V}\) (c) \(4.28 \mathrm{~V}\) (d) \(6.42 \mathrm{~V}\)

\(A+B \rightarrow\) products \begin{tabular}{|l|l|l|} \hline\([A]\) & {\([B]\)} & Rate \\ \hline \(0.1\) & \(0.1\) & \(x\) \\ \hline \(0.1\) & \(0.2\) & \(4 x\) \\ \hline \(0.4\) & \(0.2\) & \(16 x\) \\ \hline \end{tabular} What is the order of the reaction ? (a) 1 (b) 2 (c) 3 (d) 4

From the following list of ions, select the one which is discharged in preference to the others during electrolysis? (a) \(\mathrm{SO}_{4}^{2-}\) b) \(\mathrm{NO}_{3}^{-}\) c) \(\mathrm{OH}\) d) \(\mathrm{Cl}\)

If equivalent conductances of \(\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}\) and \(\mathrm{CaCl}_{2}\) are \(x\) and \(y\) respectively, the values of their molar conductances are respectively (a) \(3 x\) and \(3 y\) (b) \(6 x\) and \(2 y\) (c) \(6 x\) and \(6 y\) (d) \(x\) and \(y\)

Give the following data for the reaction: \(X+Y \rightarrow Z\) \begin{tabular}{|c|c|c|} \hline\([X]\) & {\([Y]\)} & Rate \(\times 10^{-1} \mathrm{~ms}^{-1}\) \\ \hline \(1.0 \mathrm{M}\) & \(1.0 \mathrm{M}\) & \(0.25\) \\ \hline \(2.0 \mathrm{M}\) & \(1.0 \mathrm{M}\) & \(0.50\) \\ \hline \(1.0 \mathrm{M}\) & \(2.0 \mathrm{M}\) & \(0.25\) \\ \hline \(1.0 \mathrm{M}\) & \(3.0 \mathrm{M}\) & \(0.25\) \\ \hline \end{tabular} Which one is the rate law equation? (a) Rate \(=k[X][Y]\) (b) Rate \(=k[X]^{0}[Y]^{1}\) (c) Rate \(=k[X][Y]^{\circ}\) (d) Rate \(=k[X][Y]^{2}\).

Which of the following has the highest ionic conductivity in solution? (a) \(\mathrm{Rb}^{+}\) (b) \(\mathrm{K}^{+}\) (c) \(\mathrm{Li}^{+}\) (d) \(\mathrm{Na}^{+}\)

Conductivity water is used in conductance experiments (a) It has very low conductance (b) It has high conductance (c) It has medium conductance (d) It has zero conductance

Two colourless substances \(X\) and \(Y\) react to give a coloured substance \(Z\). The time \((t)\) taken for various initial concentrations of \(X\) and \(Y\) to produce a certain colour intensity are recorded in the table \begin{tabular}{|c|c|c|} \hline\([X] / m o l \mathrm{~L}^{-1}\) & {\([Y] / m o l \mathrm{~L}^{-1}\)} & time/s \\ \hline \(0.05\) & \(0.05\) & 44 \\ \hline \(0.05\) & \(0.10\) & 22 \\ \hline \(0.10\) & \(0.05\) & 44 \\ \hline \end{tabular} Which rate equation is consistent with these results? (a) rate \(=k[Y]^{1 / 2}\) (b) rate \(=k[X]^{1 / 2}[Y]^{1 / 2}\) (c) rate \(=k[Y]\) (d) rate \(=k[X][Y]\)