231. The value of the wave length for maximum emissive power is given by
Kirchhoff’s law
Stefan’s law
Wein’s law
Planck’s law
✅ The correct answer is option C.
Heat Transfer, Refrigeration and Air Conditioning MCQs
232. If a gas is to be liquified, its temperature must be
increased to a value above its critical temperature
reduced to a value below its critical temperature
equal to critical temperature
none of the above
✅ The correct answer is option C.
233. During sensible heating of air, specific humidity remains constant.
Agree
Disagree
✅ The correct answer is option A.
234. The thermal diffusivity for gases is generally __________ those for liquids.
equal to
less than
greater than
✅ The correct answer is option C.
235. The leakage in a refrigeration system using freon is detected by
halide torch
sulphur sticks
soap and water
all of these
✅ The correct answer is option A.
236. The ratio of surface convection resistance to the internal conduction resistance is known as
Grashoff number
Biot number
Stanton number
Prandtl number
✅ The correct answer is option B.
238. A vapour absorption refrigerator uses __________ as a refrigerant.
water
ammonia
freon
aqua-ammonia
✅ The correct answer is option D.
239. Fouling factor is used
in heat exchanger design as a safety factor
in case of Newtonian fluids
when a liquid exchanges heat with a gas
none of the above
✅ The correct answer is option A.
240. For air conditioning the operation theatre in a hospital, the percentage of outside air in the air supplied is
zero
20
50
100
✅ The correct answer is option D.