Chemical Engineering Basics

291. Half life of a radioactive isotope corresponds to the time required for half of the __________ to decay.

  1. Atoms
  2. Neutrons
  3. Nucleons
  4. Electrons

Correct answer: (A)
Atoms

292. Hardening of steel is not possible, unless it is heated __________ critical point.

  1. Above the highest
  2. Above the lowest
  3. Between the first & second
  4. Between the second & third

Correct answer: (B)
Above the lowest

293. Heat flow across a hollow sphere of inner radius 'r1' and outer radius 'r2' is directly proportional to

  1. (γ2 - γ1)/γ1. γ2
  2. γ1. γ2/(γ2 - γ1)
  3. (γ2 + γ1)/γ1. γ2
  4. γ1. γ2/(γ2 + γ1)

Correct answer: (B)
γ1. γ2/(γ2 - γ1)

294. Heat release during phase change is observed in case of a/an

  1. Boiler
  2. Condenser
  3. Evaporator
  4. All (A), (B) & (C)

Correct answer: (B)
Condenser

295. Heat required to raise the temperature of a body by 1 °C is called its

  1. Heat capacity
  2. Specific heat capacity
  3. Thermal conductivity
  4. Water equivalent

Correct answer: (A)
Heat capacity

296. Heat transfer by __________ is almost absent in case of fluidised bed drying operation.

  1. Radiation
  2. Conduction
  3. Convection
  4. Both (B) & (C)

Correct answer: (A)
Radiation

297. Heat transfer to the water wall in a high pressure water wall type boiler furnace is mainly by

  1. Conduction
  2. Convection
  3. Radiation
  4. Both 'a' & 'b'

Correct answer: (C)
Radiation

298. Heating of ferromagnetic materials to a temperature above Curie temperature makes it

  1. Insulator for heat & electricity transmission
  2. Ferritic
  3. Behave like paramagnetic materials
  4. Superconductor

Correct answer: (C)
Behave like paramagnetic materials

299. Heating the Hypo-eutectoid steels to 30°C above the upper critical temperature line, soaking at that temperature and then cooling slowly to the room temperature to form a pearlite & ferrite structure is called

  1. Tempering
  2. Hardening
  3. Annealing
  4. Normalising

Correct answer: (C)
Annealing

300. High endurance limit of carburised machine parts is because of the fact that carburisation

  1. Suppresses any stress concentration produced in the parts
  2. Enhances the yield point of the material
  3. Introduces a compressive layer on the surface
  4. Produces a better surface finish

Correct answer: (C)
Introduces a compressive layer on the surface

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