Practice Pakistan's most useful MCQs for competitive exams

Normally, the length to diameter ratio of rotary dryers varies from 4 to 10 and for its economic operation; the number of transfer units (NTU) for such dryers varies from ?

• (A)  1.5-2.5
• (B)  3.5-5.5
• (C)  7.5-10.0
• (D)  10-15

Answer

Submitted By :Ali Uppal

Filtration rate is affected by the________________?

• (A)  Pressure drop across the cake & filter medium
• (B)  Cake & filter medium resistance
• (C)  Area of filtering surface & the viscosity of filtrate
• (D)  All

Answer

Submitted By :Ali Uppal

_____________ shaped roof is the most commonly used roof for cylindrical storage tanks?

• (A)  Conical
• (B)  Flat
• (C)  Dome
• (D)  Umbrella

Answer

Submitted By :Ali Uppal

The minimum shell thickness for tank ≤ 15 metres diameter is limited to _______________ mm, for reasons of elastic stability?

• (A)  2
• (B)  5
• (C)  10
• (D)  15

Answer

Submitted By :Ali Uppal

A ‘rupture disc’ is provided in chemical equipments as an accessory meant for ___________________?

• (A)  Relieving excess pressure
• (B)  Creating turbulence
• (C)  Enhancing mixing rate
• (D)  Avoiding vortex formation

Answer

Submitted By :Ali Uppal

Elastic failure of a material occurs, when the tensile stress equals yield strength, yield point or the elastic limit. Also, the elastic failure occurs according to maximum strain theory, when the maximum tensile strain equals (where, ζ = yield strength and E = modulus of elasticity) ?

• (A)  E
• (B)  ζ
• (C)  ζ/E
• (D)  E/ζ

Answer

Submitted By :Ali Uppal

Low pressure steam (with saturation temperature between 105 to 120°C) is usually used in the vacuum evaporators, which normally employ a vacuum of about _______________ mm Hg (referred to a 760 mm mercury barometer)?

• (A)  250
• (B)  450
• (C)  650
• (D)  750

Answer

Submitted By :Ali Uppal

A perforated plate has holes of diameter dn arranged in a pitch ph. Each hole has a tube of I.D. dt passing through it. The ligament efficiency is given by_______________?

• (A)  (ph – dh)/ph
• (B)  (ph – dh . dt/2)/ph
• (C)  (ph – dt)/ph
• (D)  (ph – dh)/dh

Answer

Submitted By :Ali Uppal

The ratio of linear stress to linear strain is termed as the ____________________?

• (A)  Modulus of elasticity
• (B)  Modulus of rigidity
• (C)  Bulk modulus
• (D)  None of these

Answer

Submitted By :Ali Uppal

Liquid redistribution should be done in a packed tower packed with raschig rings every 6 metres or ______________ times the column diameter, whichever is lower?

• (A)  2.5-3.0
• (B)  5-7.5
• (C)  10-12.5
• (D)  15-20

Answer

Submitted By :Ali Uppal