Practice Pakistan's most useful MCQs for competitive exams

The rate constant of a first order reaction depends on the ________________?

• (A)  Concentration of the reactant
• (B)  Temperature
• (C)  Concentration of the product
• (D)  Time

Answer

Submitted By :Ali Uppal

The units of frequency factor in Arrhenius equation_________________?

• (A)  Are the same as those of the rate constant
• (B)  Depend on the order of the reaction
• (C)  Depend on temperature, pressure etc. of the reaction
• (D)  Are cycles per unit time

Answer

Submitted By :Ali Uppal

The catalytic activity of enzymes is due to their capacity to lower the ______________ energy?

• (A)  Activation
• (B)  Potential
• (C)  Kinetic
• (D)  None of these

Answer

Submitted By :Ali Uppal

In case of _____________ reactions, the reaction rate does not decrease appreciably as the reaction proceeds?

• (A)  Catalytic
• (B)  Parallel
• (C)  Series
• (D)  Auto catalytic

Answer

Submitted By :Ali Uppal

For a gaseous phase reaction, rate of reaction is equal to K. CA . CB. If the volume of the reactor is suddenly reduced to 1/4th of its initial volume, then the rate of reaction compared to the original rate will be ______________ times?

• (A)  8
• (B)  16
• (C)  1/8
• (D)  1/16

Answer

Submitted By :Ali Uppal

The effect of increasing pressure on the gaseous equilibrium of the reaction 2X + 3Y ⇌ 3X + 2Y indicates that____________________?

• (A)  Pressure has no effect
• (B)  Backward reaction is favoured
• (C)  Forward reaction is favoured
• (D)  None of these

Answer

Submitted By :Ali Uppal

At a given value of E/R (ratio of activation energy and gas constant), the ratio of the rate constants at 500°K and 400°K is 2, if Arrhenius law is used. What will be this ratio, if transition state theory is used with the same value of „E/R‟ ?

• (A)  1.6
• (B)  2
• (C)  2.24
• (D)  2.5

Answer

Submitted By :Ali Uppal

Effective diffusivity (DE) in a catalyst pellet is related to molecular diffusivity (DN) and Knudsen diffusivity (DK) as_________________?

• (A)  DE = DM + DK
• (B)  1/DE = 1/DN + DK
• (C)  DE = DM . DE
• (D)  DE = DN/DE

Answer

Submitted By :Ali Uppal

Which of the following is not a chemical step in a fluid solid catalytic reaction ?

• (A)  Surface chemical reaction
• (B)  Adsorption
• (C)  Desorption
• (D)  None of these

Answer

Submitted By :Ali Uppal

In a reversible chemical reaction having two reactants in equilibrium, if the concentration of the reactants are doubled, then the equilibrium constant will________________?

• (A)  Remain the same
• (B)  Be halved
• (C)  Also be doubled
• (D)  Become one fourth

Answer

Submitted By :Ali Uppal