CHEMICAL ENGINEERING

Question: For the air water system under ambient conditions, the adiabatic saturation temperature and the wet bulb temperature are nearly equal, because
[A].

water has a high latent heat of evaporation.

[B].

Lewis number is close to unity.

[C].

they are always equal under all circumstances.

[D].

solubility of the components of air in water is very small.

Answer: Option A

Explanation:

No answer description available for this question.

Question: In distillation column design, the McCabe-Thiele procedure is inadequate and a Ponchan-Savarit procedure is needed, when
[A].

saturated feed is not used.

[B].

an azeotrope forms.

[C].

the latent heat of vaporisation of the more and less volatile components are greatly different.

[D].

a total condenser is used.

Answer: Option D

Explanation:

No answer description available for this question.

Question: Penetration theory states that the mass transfer co-coefficient is equal to (where, De is diffusivity and ‘t’ is time)
[A].

(De.t)1/2

[B].

(De/t)1/2

[C].

(4De/πt)1/2

[D].

(4De/t)

Answer: Option C

Explanation:

No answer description available for this question.

Question: Which of the following provides maximum contact surface for a liquid-vapour system?
[A].

Packed tower

[B].

Bubble-cap plate column

[C].

Seive-plate column

[D].

Wetted wall column

Answer: Option A

Explanation:

No answer description available for this question.

Question: For the gas absorption, the height of a transfer unit, based on the gas phase is given by (G: superficial molar gas velocity, L: superficial molar liquid velocity, FG:mass transfer co-efficient, mols/m2 , a: in-terfacial area per unit volume of tower)
[A].

[B].

[C].

[D].

Answer: Option A

Explanation:

No answer description available for this question.

Question: At 750°K and 1 atm, the approximate value of Schmidt number for air is
[A].

0.01

[B].

0.1

[C].

1

[D].

10

Answer: Option B

Explanation:

No answer description available for this question.

Question: In the layout plan for a vacuum distillation unit, operating at 60 mm Hg, supported by a barometric condenser, the appropriate place for the location of vacuum drum for collecting the distillate will be
[A].

at ground level.

[B].

2 metres above the ground.

[C].

5 metres above ground.

[D].

10 metres above ground.

Answer: Option A

Explanation:

No answer description available for this question.

Question: In an operating distillation column, the
[A].

vapors and liquids are at their dew point and bubble point respectively

[B].

driving force for the liquid flow is its specific weight.

[C].

driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column.

[D].

highest temperature is encountered at the top of the column.

Answer: Option C

Explanation:

No answer description available for this question.

Question: At a fixed pressure, the humidity depends upon the partial pressure of vapor in the mixture. Humidity of a vapour free gas is __________ percent.
[A].

100

[B].

0

[C].

50

[D].

between 0 and 100

Answer: Option B

Explanation:

No answer description available for this question.

Question: In most of the vacuum crystalliser, vacuum is generally produced by means of a
[A].

suction pump

[B].

compressed air jet

[C].

steam jet ejector with a barometric condenser

[D].

none of these

Answer: Option C

Explanation:

No answer description available for this question.