Chemical Engineering Basics

221. Dryness factor of steam is defined as the ratio of the mass of vapor in the mixture to the mass of the mixture. Dryness factor of steam is measured by a __________ calorimeter.

  1. Bomb
  2. Throttling
  3. Junker's
  4. Boy's

Correct answer: (B)
Throttling

222. Dryness fraction of dry steam is

  1. 0
  2. ∞
  3. 1
  4. 0.5

Correct answer: (C)
1

223. During decarburising of a plain carbon steel, the thickness of ferrite layer growth is proportional to

  1. Time
  2. Square root of time
  3. Square of time
  4. Cube of time

Correct answer: (B)
Square root of time

224. During sensible cooling of air, its wet bulb temperature

  1. Decreases but dew point remains constant
  2. Increases but dew point remains constant
  3. Increases & the dew point decreases
  4. Decreases & the dew point increases

Correct answer: (B)
Increases but dew point remains constant

225. During sensible heating of humid air

  1. Relative humidity increases
  2. Dew point remains constant
  3. Dry bulb & wet bulb temperature increases
  4. Both 'b' & 'c'

Correct answer: (D)
Both 'b' & 'c'

226. Earing is a defect found in steels after the following metal working operation.

  1. Extrusion
  2. Rolling
  3. Deep drawing
  4. Wire drawing

Correct answer: (C)
Deep drawing

227. Electrical conductivities of semi-conductors are of the order of __________ ohm/cm.

  1. 10-3
  2. 103
  3. 10-15
  4. 1015

Correct answer: (A)
10-3

228. Electrochemical corrosion can occur, only if __________ is present in contact with metal.

  1. Air
  2. Oxygen
  3. Liquid medium
  4. Gaseous medium

Correct answer: (C)
Liquid medium

229. Electrolytic reduction cell used for conversion of calcined Al2O3 to Al is a carbon lined furnace operating at 800-900 °C. The purpose of electric current supplied to the furnace is to

  1. Achieve very high purity of aluminium (99.9%)
  2. Keep the electrolyte in liquid condition by the generation of heat
  3. Electrolytically dissociate alumina
  4. Both (B) & (C)

Correct answer: (D)
Both (B) & (C)

230. Electrometallurgical methods of metal extraction is normally used for those metals

  1. Whose oxide/ore is not reduced by carbon
  2. Which fall in the category of alkali & alkaline earth metals
  3. Which stands higher in the electrochemical series of the metal
  4. All (A), (B) & (C)

Correct answer: (D)
All (A), (B) & (C)

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