For a first-order reaction, the time required for 99.9% of the reaction to take place is nearly :

(1) 10 times that required for half of the reaction

(2) 100 times that required for two-third of the reaction

(3) 10 times that required for one-fourth of the reaction

(4) 20 times that required for half of the reaction

The rate constant for a chemical reaction that takes place at 500 K is expressed as K = A e^-1000. The activation energy of the reaction will be:

1. 100 cal/mol

2. 1000 kcal/mol

3. 10⁴ kcal/mol

4. 10⁶ kcal/mol

The concentration of reactant X decreases from 0.1 M to 0.005 M in 40 minutes. If the reaction follows first order kinetics, the rate of reaction when concentration of X is 0.01 M will be

1. 1.73 x 10^-4 M min^-1

2. 3.47 x 10^-4 M min^-1

3. 3.47 x 10^-5 M min^-1

4. 7.50 x 10^-4 M min^-1

What is the activation energy for reverse reaction on the basis of given data ?

N₂O₄(g) $\to$ 2NO₂(g)  ΔH = +54kJ

E_a(forward) = +57.2 kJ

1. -54 kJ

2.  +3.2 kJ

3. 60.2 kJ

4. 111.2 kJ

Time required to decompose half of the substance for (n)th order reaction is propotional to:-

1. 1/a^n-1

2. a^1-n

3. a^n-1

4. Both 1 and 2

 For the pseudo first order reaction A + B $\to$ P, when studied with 0.1 M of B is given by -d[A]/dt =k[A] where K = 1.85 x 10⁴ sec^-1. Calculate the value of rate constant for second order reaction :

(1) 1.85 x 10⁴

(2) 1.85 x 10^-4

(3) 1.85 x 10^-5

(4) 1.85 x 10⁵

The rate constant of a first order reaction is 10^-3 min^-1 at 27°C. The temperature coefficient of this  reaction is 2. The rate constant at 17°C will be :

(1) 10^-3 min^-1

(2) 5  x 10^-4 min^-1

(3) 2 x 10^-3 min^-1

(4) 10^-2 min^-1

The activation energy of a reaction is zero. The rate constant of the reaction is :

1. increases with an increase in temperature

2. decreases with a decrease in temperature

3. decreases with an increase in temperature

4. is nearly independent of temperature

Two reactions of the same order have equal Pre-exponential factors but their activation energies differ by 24.9 kJ/mol. Calculate the ratio between the rate constants (K₁/K₂) these reactions at 27°C :

1. 2.2 × 10⁴

2. 1/2 × 10^-4

3. 1/2 × 10⁴

4. 2.2 × 10^-4

For a first order reaction A $\to$ product :

(1)

(2)

(3)

(4)