Practice Pakistan's most useful MCQs for competitive exams

Helium-mercury method is used for the measurement of the ________________ of the catalyst?

• (A)  Surface area
• (B)  Porosity
• (C)  Pore volume
• (D)  Both

Answer

Submitted By :Ali Uppal

With increase in the space time of an irreversible isothermal reaction being carried out in a P.F. reactor, the conversion will________________?

• (A)  Increase
• (B)  Decrease
• (C)  Remain same
• (D)  Data in insufficient; can’t be predicted

Answer

Submitted By :Ali Uppal

If the rate of a chemical reaction becomes slower at a given temperature, then the__________________?

• (A)  Initial concentration of the reactants remains constant
• (B)  Free energy of activation is lower
• (C)  Entropy changes
• (D)  Free energy of activation is higher

Answer

Submitted By :Ali Uppal

For an isothermal variable volume batch reactor, the following relation is applicable for a first order irreversible reaction?

• (A)  XA = k . t
• (B)  [CA0/(1 + εA XA)] (dXA/dt) = k
• (C)  -ln(1 – XA) = kt
• (D)  εA . ln (1 – XA) = k . t

Answer

Submitted By :Ali Uppal

Which of the following is a characteristic of an ideal plug flow reactor ?

• (A)  Axial dispersion
• (B)  Flat velocity profile
• (C)  Uniform mixing
• (D)  None of these

Answer

Submitted By :Ali Uppal

According to the ‘law of mass action’, the rate of reaction is directly proportional to the__________________?

• (A)  Equilibrium constant
• (B)  Volume of the reaction vessel
• (C)  Nature of the reactants
• (D)  Molar concentration of the reactants

Answer

Submitted By :Ali Uppal

In a chemical reaction as shown in the bellow figure, it is observed that the (i) Rate of formation of ‘P’ is doubled on doubling the concentration of ‘X’ (ii) Rate of formation of ‘P’ is quadrupled on doubling the concentration of ‘Y’ (iii) Doubling the concentration of ‘Z’ does not affect the rate of formation of ‘P’ What is the order of the above chemical reaction ?

• (A)  Zeroth order
• (B)  First order
• (C)  Second order
• (D)  Third order

Answer

Submitted By :Ali Uppal

With an increase in pressure in gaseous phase chemical reactions, the fractional conversion ______________ when the number of moles decreases?

• (A)  Increases
• (B)  Decreases
• (C)  Remain unaffected
• (D)  Unpredictable from the data

Answer

Submitted By :Ali Uppal

A liquid phase reaction is to be carried out under isothermal conditions. The reaction rate as a function of conversion has been determined experimentally and is shown in the figure given below. What choice of reactor or combination of reactors will require the minimum overall reactor volume, if a conversion of 0.9 is desired ?

• (A)  CSTR followed by a PFR
• (B)  PFR followed by a CSTR
• (C)  CSTR followed by a PFR followed by a CSTR
• (D)  PFR followed by a CSTR followed by a PFR

Answer

Submitted By :Ali Uppal

What is the order of chemical reaction as shown in the bellow figure, if it is found that the reaction rate doubles on doubling the concentration of B and also the reaction rate doubles when the concentrations of both A & B were doubled and quadrupled when the concentrations of both B & C were doubled ?

• (A)  1
• (B)  2
• (C)  3
• (D)  4

Answer

Submitted By :Ali Uppal