- (A) The binary diffusivity in liquids is of the order of 10-5 cm2/sec
- (B) Molecular diffusion in solid is much faster than that in liquids
- (C) Particles movement from higher concentration to lower concentration takes place in diffusion process
- (D) According to Poiseuille’s law, the permeability decreases with increase in temperature for flow of a gas through a given capillary
Exam preparation MCQs with answers
Practice Pakistan's most useful MCQs for competitive exams
Prepare for NTS, PPSC, FPSC and subject-wise tests with fresh multiple choice questions, clear options and quick answer reveal.
Latest MCQs
- (A) In case of induced draft cooling tower, the fan is placed at the top of the tower
- (B) Effectiveness of forced draft cooling tower is reduced by the recirculation of the humid and hot discharged air
- (C) A natural draft cooling tower is recommended to be used, when the air humidity is low and air temperature is also low
- (D) Effectiveness of a mechanical draft cooling tower is reduced with increase in air wet-bulb temperature
- (A) Change in barometric pressure does not affect the relative humidity
- (B) In case of a packed tower, the operating velocity is about half of the flooding velocity, generally
- (C) ‘Elution’ means the desorption of the adsorbed solute by a solvent
- (D) The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity
- (A) A horizontal line on the humidity chart indicates the temperature changes at constant molal humidity
- (B) When water is cooled from 80 to 70°C by exposure to the air with a wet bulb temperature of 60°C, then both the approach & the range would be 10°C
- (C) For unsaturated air-water vapor mixture at atmospheric conditions, the wet bulb temperature & adiabatic cooling lines are the same
- (D) Relative saturation of unsaturated mixture of water vapor & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure
- (A) The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are the same for NSc = NPr= 1
- (B) 1 Nm3 of dry air is lighter than 1Nm3 of humid air
- (C) The Lewis number of a mixture is unity, when the thermal diffusivity is equal to the mass diffusivity
- (D) An Azeotropic mixture of two liquids has boiling point higher than either of them, when it shows negative deviation from Raoult’s Law
- (A) Higher hold up of the solid in the rotary dryer results in better exposure of the solids to the gas
- (B) The ‘Hatta number’ is important in problems involving gas absorption without chemical reaction
- (C) For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion
- (D) Total reflux in case of distillation operation requires infinite number of plates for a binary system separation
- (A) Constant pressure distillation cannot separate an Azeotropic mixture
- (B) Relative volatility of a binary mixture changes appreciably with the minor change in temperature
- (C) The relative volatility of a binary mixture at Azeotropic composition is unity
- (D) Flash distillation is practised on wide spread scale in petroleum refinery
- (A) P
- (B) 1/P
- (C) 1/√P
- (D) √P
- (A) Decreases
- (B) Increases
- (C) Depends on the extent of heating
- (D) Remain unchanged
- (A) A pure component
- (B) A binary mixture
- (C) A ternary mixture
- (D) Partially miscible ternary system
