In a first order reaction A $\stackrel{ }{\to }$ B, if k is rate constant and initial concentration of the reactant A is 0.5 M then the half-life is :

(1) $\frac{0.693}{0.5k}$

(2) $\frac{\log 2}{k}$

(3) $\frac{\log 2}{k\sqrt{0.5}}$

(4) $\frac{\ln 2}{k}$

If a first-order reaction reaches 60% completion within 60 minutes, approximately how much time would it take for the same reaction to reach 50% completion? (log 4=0.60, log 5=0.69)

1. 50 min

2. 45 min

3. 60 min

4. 30 min

For the reaction 2A + B $\stackrel{ }{\to }$ 3C + D which of the following does not express the reaction rate ?

(1) $-\frac{\mathrm{d}\left[\mathrm{C}\right]}{3\mathrm{dt}}$

(2) $-\frac{\mathrm{d}\left[\mathrm{B}\right]}{\mathrm{dt}}$

(3) $\frac{\mathrm{d}\left[\mathrm{D}\right]}{\mathrm{dt}}$

(4) $-\frac{\mathrm{d}\left[\mathrm{A}\right]}{2\mathrm{dt}}$

The units of rate constant and rate of reaction are same for: 

1. First order reaction 

2. Second order reaction 

3. Third order reaction 

4. Zero order reaction 

Rate constant K= $1.2\times {10}^3$ mol L^-1 s^-1 and $E_a =2.0\times {10}^{2}KJ mo{l}^{-1}. When T\to \infty$, A is equal to 

(1) 2.0 $\times {10}^2\hspace{0.17em}mo{l}^{-1}{L}^{-1}{s}^{-1}$

(2) 1.2 $\times$ 10³ mol L^-1 s^-1

(3) 3.3 $\times$ 10³  mol L^-1 s^-1

(4) 2.4 $\times$ 10³ mol L^-1 s^-1

The effect of a catalyst in a chemical reaction is to change the 

1. Acivation energy.

2. Equilibrium concentration.

3. Heat of reaction.

4. Final products.

When the concentration of reactant was made 4 times rate of reaction becomes 8 times. The order of reaction with respect to that reactant is 

1. 2

2. 3

3. 1

4. 1.5

The bromination of acetone that occurs in acid solution is represented by this equation.

${\mathrm{CH}}_3{\mathrm{COCH}}_3\left(\mathrm{aq}\right) + {\mathrm{Br}}_2\left(\mathrm{aq}\right) \stackrel{ }{\to }{\mathrm{CH}}_3{\mathrm{COCH}}_2\mathrm{Br}\left(\mathrm{aq}\right) + {\mathrm{Br}}^{-}\left(\mathrm{aq}\right)$

These kinetic data were obtained for given reaction concentrations. 

                   Initial concentrations, M

  $\left[{\mathrm{CH}}_3{\mathrm{COCH}}_3\right]$                $\left[{\mathrm{Br}}_2\right]$         $\left[{\mathrm{H}}^{+}\right]$

       0.30                        0.05           0.05

       0.30                        0.10           0.05

       0.30                        0.10           0.10

       0.40                        0.05           0.20

Initial rate, disappearance of Br₂, Ms^-1

                        5.7X10^-5

                        5.7X10^-5

                        1.2X10^-4

                        3.1X10^-4

Based on these data, the rate equation is

1. Rate = k [CH₃COCH₃] [H⁺]

2. Rate = k [CH=COCH₃][Br₂]

3. Rate = k [CH₃COCH₃][Br₂][H⁺]²

4. Rate = k [CH₃COCH₃][Br₂][H⁺]

The rate constants k₁ and k₂ for two different reactions are 10¹⁶ e^-2000/T and 10¹⁵ e^-1000/T  , respectively. The temperature at which k₁=k₂ is:

(1) 1000 K

(2) $\frac{2000}{2.303}\mathrm{K}$

(3) 2000K

(4) $\frac{1000}{2.303}\mathrm{K}$

In the reaction, BrO^-₃(aq) + 5Br^-(aq) + 6H⁺ $\to$3Br₂(l) + 2H₂O(l)

The rate of appearance of bromine (Br₂) is related to rate of disappearance of bromide

ions as following 

1. d[Br₂]/dt = -(3/5)d[Br^-]/dt

2. d[Br₂]/dt = (5/3)d[Br^-]/dt

3. d[Br₂]/dt = -(5/3)d[Br^-]/dt

4. d[Br₂]/dt = (3/5)d[Br^-]/dt