Chemical Engineering Mcqs

A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300°C and allowed to cool in natural air. Which one will cool the slowest ?

(A) Cube
(B) Plate
(C) Sphere
(D) All will cool at the same rate

Submitted By :Ali Uppal

A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions? Assume that the conductive heat transfer co-efficient is infinitely large ?

(A) 5 minutes
(B) 10 minutes
(C) 20 minutes
(D) 40 minutes

Submitted By :Ali Uppal

Presence of a non-condensing gas in a condensing vapour___________________?

(A) Increases the rate of condensation
(B) Decreases thermal resistance
(C) Is desirable to increase the film co-efficient
(D) None of these

Submitted By :Ali Uppal

The separation of liquid droplets from the vapor is done by a/an _____________ in the evaporators?

(A) Steam ejector
(B) Entrainment separator
(C) Compressor
(D) Vacuum pump

Submitted By :Ali Uppal

For the same heat transfer area and the terminal conditions, the ratio of the capacities of a single effect evaporator to a triple effect evaporator is_________________?

(A) 3
(B) 0.33
(C) 1
(D) 1.33

Submitted By :Ali Uppal

According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor) ?

(A) 2f
(B) f
(C) f/2
(D) f/4

Submitted By :Ali Uppal

The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)?

(A) αT
(B) α × 1/T
(C) α T4
(D) Independent of T

Submitted By :Ali Uppal

The equivalent diameter for the annulus of a double pipe heat exchanger, whose inner pipe has fins on the outside is ______________ compared to the same size pipes without fins?

(A) More
(B) Less
(C) Same
(D) Unpredictable

Submitted By :Ali Uppal

A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because__________________?

(A) Total heat transfer area of all the effects is -less than that in a single effect evaporator system
(B) Total amount of vapor produced per Kg of feed steam in a multiple effect system is much higher than in a single effect
(C) Boiling point elevation in a single effect system is much higher than that in any effect in a multi-effect system
(D) Heat transfer co-efficient in a single effect is much lower than that in any effect in a multieffect system

Submitted By :Ali Uppal

Grashoff number, which is defined as g . β (Ts – T∞) ρ2. L3/μ2, is proportional to the ratio of buoyancy force to ____________ force?

(A) Viscous
(B) Elastic
(C) Inertial
(D) None of these

Submitted By :Ali Uppal

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