Practice Pakistan's most useful MCQs for competitive exams

Grizzlies are used for separating _____________ solids?

• (A)  Coarse
• (B)  Fine
• (C)  Any size
• (D)  None of these

Answer

Submitted By :Ali Uppal

In closed circuit grinding as compared to open circuit grinding, the_________________?

• (A)  Specific surface of product is more
• (B)  Product has lesser size uniformity
• (C)  Production rate at a given limiting size is lower
• (D)  Operation is economical

Answer

Submitted By :Ali Uppal

In bag filters, filter fabrics are never made of__________________?

• (A)  Metallic wire woven mesh
• (B)  Polyester fibres
• (C)  Cotton fibres
• (D)  Nylon fibres

Answer

Submitted By :Ali Uppal

For crushing of solids, the Rittinger’s law states that the work required for crushing is proportional to __________________?

• (A)  The new surface created
• (B)  The size reduction ratio
• (C)  The change in volume due to crushing
• (D)  None of these

Answer

Submitted By :Ali Uppal

Which of the following screens has the maximum capacity ?

• (A)  Grizzlies
• (B)  Trommels
• (C)  Shaking screen
• (D)  Vibrating screen

Answer

Submitted By :Ali Uppal

In case of the irreversible unimolecular type, first order reaction, the fractional conversion at any time for constant volume system as compared to variable volume system is___________________?

• (A)  More
• (B)  Less
• (C)  Same
• (D)  Either

Answer

Submitted By :Ali Uppal

Volume change for unimolecular type first order reaction as shown in the bellow figure, increases _____________ with time?

• (A)  Linearly
• (B)  Exponentially
• (C)  Parabolically
• (D)  Logarithmically

Answer

Submitted By :Ali Uppal

Brunauer, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed. Which of the following postulates is not used to derive BET equation ?

• (A)  Langmuir’s assumption applies to every adsorbed layer
• (B)  There is no dynamic equilibrium between successive layer
• (C)  The adsorbed layer may be polymolecular in thickness and the heat of adsorption in each layer (except the first one) is involved in each of the evaporation process
• (D)  None of these

Answer

Submitted By :Ali Uppal

An example of autothermal reactor operation is______________________?

• (A)  Sulphur dioxide oxidation
• (B)  Ethylene oxidation
• (C)  Benzene oxidation
• (D)  Ammonia synthesis

Answer

Submitted By :Ali Uppal

A first order reaction is to be treated in a series of two mixed reactors. The total volume of the two reactors is minimum, when the reactors are_____________________?

• (A)  Equal in size
• (B)  Of different sizes
• (C)  Of such size that the ratio of their volumes is < 5
• (D)  None of these

Answer

Submitted By :Ali Uppal