Practice Pakistan's most useful MCQs for competitive exams

Maximum equilibrium conversion for endothermic reaction is obtained at the ______________ temperature?

• (A)  Highest possible
• (B)  Lowest possible
• (C)  Intermediate
• (D)  Room

Answer

Submitted By :Ali Uppal

A space velocity of 5 hr-1 means that ___________________?

• (A)  Five reactor volumes of feed (at specified conditions) are being fed into the reactor per hour
• (B)  After every 5 hours, reactor is being filled with the feed
• (C)  Cent per cent conversion can be achieved in at least 5 hours
• (D)  A fixed conversion of a given batch of feed takes 5 hours

Answer

Submitted By :Ali Uppal

The reaction A → B is conducted in an adiabatic plug flow reactor (PFR). Pure A at a concentration of 2 kmol/m3is fed to the reactor at the rate of 0.01 m3 /s and at a temperature of 500 K. If the exit conversion is 20%, then the exit temperature (in k) is (Data: Heat of reaction at 298 K = – 50000 kJ/ kmole of A reacted Heat capacities CPA = CPB = 100kJ/kmole. K (may be assumed to be independent of temperature)) ?

• (A)  400
• (B)  500
• (C)  600
• (D)  1000

Answer

Submitted By :Ali Uppal

For the non catalytic reaction of particles with surrounding fluid, the same needed to achieve the same fractional conversion for particles of different unchanging sizes is proportional to the particle diameter, when the ________________ is the controlling resistance?

• (A)  Film diffusion
• (B)  Diffusion through ash layer
• (C)  Chemical reaction
• (D)  Either

Answer

Submitted By :Ali Uppal

For every 10°C rise in temperature, the rate of chemical reaction doubles. When the temperature is increased from 30 to 70°C, the rate of reaction increases ______________ times?

• (A)  8
• (B)  12
• (C)  16
• (D)  32

Answer

Submitted By :Ali Uppal

Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction ?

• (A)  Ash resistance
• (B)  Gas film and pore surface diffusion resistances for reactants
• (C)  Surface phenomenon resistance
• (D)  Gas film and pore surface diffusion resistances for products

Answer

Submitted By :Ali Uppal

The minimum energy required to allow a chemical reaction to proceed is termed as the ‘threshold energy ‘. Chemical reactions with low activation energy are ________________?

• (A)  Always irreversible
• (B)  Insensitive to temperature changes
• (C)  Mostly irreversible
• (D)  Highly temperature sensitive

Answer

Submitted By :Ali Uppal

The rate at which a chemical substance reacts is proportional to its____________________?

• (A)  Active mass
• (B)  Equivalent weight
• (C)  Molecular weight
• (D)  None of these

Answer

Submitted By :Ali Uppal

For any reaction, we may write conversion as a function of______________________?

• (A)  Time
• (B)  Temperature
• (C)  Concentration
• (D)  All

Answer

Submitted By :Ali Uppal

When a high liquid hold up is required in a reactor for gas liquid reaction, use ______________ column?

• (A)  Packed
• (B)  Spray
• (C)  Tray
• (D)  Bubble

Answer

Submitted By :Ali Uppal