The expression for velocity constant for the second order reaction is

• k = $\frac{2.303}{\mathrm{t}} {\log }_{10} \frac{\mathrm{a}}{\mathrm{a} -\mathrm{x}}$

• k = $\frac{1}{\mathrm{t}}\frac{\mathrm{x}}{\mathrm{a}(\mathrm{a} - \mathrm{x})}$

• k = $\frac{1}{\mathrm{t}}\frac{{\mathrm{x}}^2}{{\mathrm{a}}^2 [\mathrm{a} - \mathrm{x}{]}^2}$

• None of the above

The unit of rate constant for second order reaction is

• s^-1

• mol / L^-1

• L mol^-1 s^-1

• L² mol^-2 s

For a reaction of the type A + B → products, it is observed that doubling the concentration of A causes the reaction rate to be four times as great, but doubling the amount of B does not affect the rate. The rate equation is

• Rate = k[A][B]

• Rate = k[A]²

• Rate = k [A]²[B]

• Rate = k [A]²[B]²

Unit of first order rate constant is

• mol L s

• mol^-1 L^-1 s^-1

• mol L^-1 s^-1

• s^-1, min^-1 etc

Which of the following expression is correct for the first order reactions (C₀ refers to initial concentration and t_1/2 refers to half-life time)?

• ${\mathrm{t}}_{1/2} \infty {\mathrm{C}}_0^0$

• ${\mathrm{t}}_{1/2} \infty {\mathrm{C}}_0^{-1}$

• ${\mathrm{t}}_{1/2} \infty {\mathrm{C}}_0$

• ${\mathrm{t}}_{1/2} \infty {\mathrm{C}}_0^{1/2}$

3A → 2B, rate of reaction $\frac{+\mathrm{d} \left(\mathrm{B}\right)}{\mathrm{dt}}$ is equal to

• $\frac{-3}{2}\frac{\mathrm{d}\left[\mathrm{A}\right]}{\mathrm{dt}}$

• $-\frac{2}{3}\frac{\mathrm{d}\left[\mathrm{A}\right]}{\mathrm{dt}}$

• $-\frac{1}{3}\frac{\mathrm{d}\left[\mathrm{A}\right]}{\mathrm{dt}}$

• $+2\frac{\mathrm{d}\left[\mathrm{A}\right]}{\mathrm{dt}}$

157.

2A → B + C

It would be a zero order reaction when

• the rate of reaction is proportional to square of concentration of A

• the rate of reaction remains same at any concentration of A

• the rate remains unchanged at any concentration of B and C

• the rate of reaction doubles if concentration of B is increased to double

8.0 g of a radioactive substance remains 0.5 g in 1 h. What is its half-life period?

• 10min

• 15min

• 30min

• None of these

The reaction A → B follows first order kinetics. The time taken for 0.8 mole of A to produce 0.6 mole of B is 1 h. What is the time taken for conversion of 0.9 mole of A to produce 0.675 mole of B?

• 1 h

• 0.5 h

• 0.25 h

• 2 h

1.0 L of 2.0 M acetic acid is mixed with 1.0 L of 3.0 Methyl alcohol. The reaction is CH₃COOH + C₂H₅OH $\rightleftharpoons$ CH₂COOC₂H₅ + H₂O. 1.0 L of 2.0 M acetic acid is mixed with 1.0 L of 3.0 Methyl alcohol. The reaction is

• 0.5 times

• 2.0 times

• 4.0 times

• 0.25 times