On This Page
This set of Mass Transfer Multiple Choice Questions & Answers (MCQs) focuses on Mass Transfer Set 3
Q1 | Which of the following processes is followed by unsaturated air (with dry bulb temperature 12°C and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40°C?
- Humidification only
- Heating only
- Both heating and humidification
- Evaporative cooling
Q2 | The velocity, concentration and temperature boundary, for the boundary layer developmenton a flat plate during connective mass transfer will be same, if
- NSc = 1
- NSc = NPr = NLe
- NPr = NLe
- NSc = NLe
Q3 | Pick out the wrong statement. Generally for physical adsorption, a gas of
- Higher molecular weight is adsorbed in preference to a gas of low molecular weight
- High critical temperature is adsorbed in preference to a gas of low critical temperature
- Low volatility is adsorbed in preference to a gas of high volatility
- None of these
Q4 | Co-current absorbers are usually used when the gas to be dissolved in the liquid is
- Sparingly soluble
- Highly soluble
- A pure substance
- A mixture
Q5 | Molecular sieves are regenerated by heating to __________ °C.
- < 150
- 200-330
- > 500
- > 1000
Q6 | In triangular co-ordinates, the ternary composition point falls __________ of the triangle.
- In the corners
- Inside
- On the sides
- None of these
Q7 | When acetone is added in a two layer mixture of methyl isobutyl ketone and water at 30°C, the acetone distributes between the two layers and the composition of the layer follows two solubility curves. For this system,
- As the acetone concentration increases, the solubility curves approach each other
- Both the phases become iden called the plait point
- The distribution curve which is a plot between x (acetone concentration in one phase) and y (acetone concentration in other phase) is analogous to x-y curve used in distillation and absorption terminates on the x = y diagonal at the concentration of the plait point
- All (A), (B) and (C)
Q8 | During sensible cooling process
- Relative humidity decreases
- Relative humidity increases
- Wet bulb temperature decreases
- Both (B) and (C)
Q9 | For stripping of a gas in a counter current stripper, the operating line
- Lies above the equilibrium curve
- Lies below the equilibrium curve
- Can lie above or below the equilibrium curve
- Is always parallel to the equilibrium curve
Q10 | The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient (Kc) for the same system is.
- 100
- 10
- 5
- 1
Q11 | The boiling points of pure components of a binary system __________ with increase in total pressure of the system.
- Decreases
- Increases
- Remains unchanged
- May increase or decrease, depends on the system
Q12 | In gas-liquid contact operation, the number of ideal stages, N = (xa - xb)/(xb - x*b). This is true when the stripping factor 'S' is
- S > 1
- S < 1
- S = 1
- S = ?
Q13 | Large scale usage of flash distillation is practised in
- Soap manufacturing
- Ammonia synthesis plant
- Polymerisation industry
- Petroleum refining
Q14 | Drying of a solid involves __________ transfer.
- Only heat
- Only mass
- Both heat and mass
- None of these
Q15 | Desulphurisation of petrol is done in a
- Bollman extractor
- Rotating disc extractor
- Packed extraction column
- Plate type extraction column
Q16 | Pick out the wrong statement
- Co-current absorbers are usually used, when the gas to be dissolved in the liquid is a pure substance
- In case of gas absorption, HETP is equal to HTU, when both the operating line & the equilibrium lines are parallel
- Hatta number is important in case of gas absorption with chemical reaction
- In actual practice, absorption is an endothermic process, while stripping is an exothermic process
Q17 | Which of the following increases during evaporative cooling process with recirculated water supply?
- Wet bulb temperature
- Relative humidity
- Partial pressure of vapour
- Both (B) and (C)
Q18 | Operating velocity in a packed tower is usually __________ the flooding velocity.
- Half
- Twice
- Equal to
- More than
Q19 | For gas absorption, low viscosity solvents are preferred, because of their
- Better flow characteristics
- Low pumping pressure drop
- Rapid absorption rates
- All (A), (B) and (C)
Q20 | Which of the following is used for the concentration of rubber latex?
- Agitated film evaporator
- Long tube vertical evaporator
- Short tube evaporator
- Calandria
Q21 | Pressure drop through plate tower as compared to that through packed tower, for the same duty will be
- Less
- More
- Equal
- Either (A) or (B); depends on the packing height
Q22 | In case of absorption & stripping, the interface of the liquid & gas phases are present in equilibrium, when the diffusional resistance of __________ is zero.
- Interface
- Gas phase
- Liquid phase
- All 'a', 'b' & 'c'
Q23 | Henry's law states that the
- Partial pressure of a component over a solution is proportional to its mole fraction in the liquid
- Partial pressure of a component over a solution is proportional to the mole fraction in the vapour
- Vapour pressure is equal to the product of the mole fraction and total pressure
- Partial pressure is equal to the product of the mole fraction and total pressure
Q24 | The change in enthalpy, when a unit quantity of gas is absorbed by relatively large quantity of adsorbent (on which a definite concentration of the adsorbed gas already exists) is termed as the
- Differential heat of adsorption
- Heat of wetting
- Integral heat of adsorption
- None of these
Q25 | A 25 cm × 25 cm × 1 cm flat sheet weighing 1.2 kg initially was dried from both sides under constant drying rate conditions. It took 1500 seconds for the weight of the sheet to reduce to 1.05 kg. Another 1m × 1m × 1cm flat sheet of the same material is to be dried from one side only. Under the same constant drying rate conditions, the time required for drying (in seconds) from its initial weight of 19.2 kg to 17.6 kg is
- 1000
- 1500
- 2000
- 2500