Chemical Engineering Basics

81. A solar cell converts the sunlight directly into __________ energy.

  1. Thermal
  2. Electrical
  3. Mechanical
  4. Chemical

Correct answer: (B)
Electrical

82. A solid aluminium ball, when quenched in a water bath maintained at 40°C, cools down from 550°C to 450°C in 20 seconds. The expected temperature of the ball after next 20 seconds may be about __________ °C.

  1. 370
  2. 340
  3. 320
  4. 300

Correct answer: (A)
370

83. A solution which resists change in its pH value on addition of acid/alkali is called the __________ solution.

  1. Neutral
  2. Ideal
  3. Buffer
  4. Zero pH

Correct answer: (C)
Buffer

84. A spring material should have low

  1. Elastic limit
  2. Deflection value
  3. Fatigue resistance
  4. None of these

Correct answer: (D)
None of these

85. A steam carrying pipeline is insulated with two layers of insulating materials with the inferior insulation material forming the inner part. If the two insulating layers are interchanged, the heat conducted will

  1. Increase
  2. Decrease
  3. Remain unaffected
  4. May increase or decrease; depends on the thickness of each layer

Correct answer: (C)
Remain unaffected

86. A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place

  1. The better insulation material should be put just next to pipe (i.e., inside)
  2. The better insulating material should be put outside
  3. Either of the insulating material could be put on either side
  4. Steam temperature is considered before deciding as to which insulating material is to be put inside (i.e., just next to the pipe)

Correct answer: (A)
The better insulation material should be put just next to pipe (i.e., inside)

87. A thin, flat & square plate measuring 2 m × 2 m is freely hanging in ambient air at 25°C. It is exposed to the solar radiation falling on one side of the plate at the rate of 500 W/m2. The plate temperature will remain constant at 30°C, if the convective heat transfer co-efficient is __________ W/m2 °C.

  1. 50
  2. 100
  3. 150
  4. 200

Correct answer: (B)
100

88. About __________ ton of coke is required in a cupola to produce one ton of casting.

  1. 0.03
  2. 0.3
  3. 0.8
  4. 1.5

Correct answer: (B)
0.3

89. Absolute zero pressure can be attained at a temperature of

  1. 0°C
  2. 50°K
  3. 0°R
  4. None of these

Correct answer: (C)
0°R

90. Absolute zero, pressure will occur, when the molecular momentum of the system becomes zero. A liquid will cease to exist as liquid at

  1. High vacuum
  2. Zero pressure
  3. 0°K
  4. Earth's centre

Correct answer: (B)
Zero pressure

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