# A 2 kW, 40 litre water heater is switched on for 20 minutes. The heat capacity Cp for water is 4.2 kJ/kg K. Assuming all the electrical energy has gone into heating the water, increase of the water temperature in degree centigrade is

1.    2.7

2.   4.0

3.   14.3

4.  25.25

4

14.3

Explanation :
No Explanation available for this question

# An industrial heat pump operates between the temperatures of 27°C and -13°C. The rates of heat addition and heat rejection are 750 W and 1000W, respectively. The COP for the heat pump is

1.  7.5

2.   6.5

3.  4.0

4.  3.0

4

4.0

Explanation :
No Explanation available for this question

# A plate having 10 cm2  area each side is hanging in the middle of a room of 100m2 total surface area. The plate temperature and emissivity are respectively 800K and 0.6. the temperature and emissivity values for the surfaces of the room are 300K and 0.3 respectively. Boltzmann’s constant σ=5.67x10-8 W/m2K4. The total heat loss from the two surfaces of the plate is

1.  13.66 W

2.   27.32 W

3.  27.87 W

4.  13.66 W

4

27.32 W

Explanation :
No Explanation available for this question

# For air with a relative humidity of 80%

1.  the dry bulb temperature is less than the wet bulb temperature

2.   the dew point temperature is less than wet bulb temperature

3.  the dew point and wet bulb temperatures are equal

4.  the dry bulb and dew point temperatures are equal

4

the dew point temperature is less than wet bulb temperature

Explanation :
No Explanation available for this question

# For a spark ignition engine, the equivalence ratio (0) of mixture entering the combustion chamber has values.

1.   ø < 1 for idling and ø > 1 for peak power conditions.

2.  ø > 1 for both idling and peak power conditions

3.  ø > 1 for idling and ø < 1 for peak power conditions.

4.   ø < 1 for both idling and peak power conditions.

4

ø > 1 for both idling and peak power conditions

Explanation :
No Explanation available for this question

# A diesel engine is usually more efficient than a spark ignition engine because

1.   diesel being a heavier hydrocarbon, releases more heat per kg than gasoline

2.  the air standard efficiency of diesel cycle is higher than the Otto cycle, at a fixed compression ratio

3.   the compression ratio of a diesel engine is higher than that of an SI engine (d) self ignitiontemperature of diesel is higher than that of gasoline

4.  self ignition temperature of diesel is higher than that of gasoline

4

the compression ratio of a diesel engine is higher than that of an SI engine (d) self ignitiontemperature of diesel is higher than that of gasoline

Explanation :
No Explanation available for this question

# In a Rankine cycle, regeneration results in higher efficiency because

1.  pressure inside the boiler increases

2.  heat is added before steam enters the low pressure turbine

3.  average temperature of heat addition in the boiler increases

4.  total work delivered by the turbine increases

4

average temperature of heat addition in the boiler increases

Explanation :
No Explanation available for this question

# During heat treatment of steel, the hardness of various structures in increasing order is

1.  marten site, fine pearlite, coarse pearlite, spherodite

2.   fine pearlite, coarse pearlite, spherodite, martensite

3.  martensite, coarse pearlite, fine pearlite, spherodite

4.  spherodite, coarse pearlite, fine pearlite, martensite

4

spherodite, coarse pearlite, fine pearlite, martensite

Explanation :
No Explanation available for this question

# Hardness of green sand mould increases with

1.  increase in moisture content beyond 6 percent

2.  increase in permeability

3.  decrease in permeability

4.  increase in both moisture content and permeability

4

decrease in permeability

Explanation :
No Explanation available for this question

1.  3500°C

2.   3200°C

3.   2900°C

4.   2550°C

4