1393. Boiling point of a solution according to Duhring’s rule is a linear function of the __________ of water.
Boiling point (at the same pressure)
Viscosity
Density
Thermal conductivity
✅ The correct answer is option A.
1396. The local surface conductance for laminar film condensation on vertical surface is (where, t = film thickness)
∝ t
∝ 1/t
∝ √t
Independent of ‘t’
✅ The correct answer is option B.
1398. If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will
Increase by 1.8 times
Decrease by 22
Increase by 216
Remain unchanged
✅ The correct answer is option C.
1400. In Joule’s experiment, an insulated container contains 20 kg of water initially at 25°C. It is stirred by an agitator, which is made to turn by a slowly falling body weighing 40 kg through a height of 4 m. The process is repeated 500 times. The acceleration due to gravity is 9.8 ms⁻². Neglecting the heat capacity of agitator, the temperature of water (in °C) is
40.5
34.4
26.8
25
✅ The correct answer is option B.
1402. Which of the following has maximum thermal conductivity?
Iron
Coal
Nitrogen
Tar
✅ The correct answer is option A.
1404. For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally
Decreases
Increases
Remains unchanged
Increases exponentially
✅ The correct answer is option A.
1406. Which of the following is the most widely used heat insulating material for pipelines carrying steam?
Tar dolomite bricks followed by asbestos
Fireclay refractory followed by aluminium sheet
Cotton followed by aluminium foil
85% magnesia cement and glass wool
✅ The correct answer is option D.
1408. In a co-current double pipe heat exchanger used for condensing saturated steam over the inner tube, if the entrance and exit conditions of the coolant are interchanged, then the rate of condensation will
Increase
Decrease
Remain unchanged
Either increase or decrease; depends on the coolant flow rate
✅ The correct answer is option C.
1371. Unsteady state heat conduction occurs, when
Temperature distribution is independent of time
Temperature distribution is dependent on time
Heat flows in one direction only
Three dimensional heat flow is concerned
✅ The correct answer is option B.