### SSC JE CIVIL ENGINEERING 2 March 2017 paper(morning shift)

1 - Condensing temperature in a refrigerator is the temperature _
1) of cooling medium
2) of freezing zone
3) of evaporator
4) at which refrigerant gas becomes liquid
Correct Answer: at which refrigerant gas becomes liquid

2 - With an increase in the thickness of insulation around a circular pipe, heat loss to surroundings due to _
1) convection increases, where as due to conduction decreases
2) convection decreases, where as due to conduction increases
3) both convection and conduction decreases
4) both convection and conduction increases
Correct Answer: convection increases, where as due to conduction decreases

3 - For air with a relative humidity of 80% _
1) dry bulb temperature is less than the wet bulb temperature
2) dew point temperature is less than wet bulb temperature
3) dew point and wet bulb temperatures are equal
4) dry bulb and dew point temperatures are equal
Correct Answer: dew point temperature is less than wet bulb temperature

4 - A football was inflated to a gauge pressure of 1 bar when the ambient temperature was 15°C. When the game started next day, the air temperature at the stadium was 5°C. Assume that the volume of the football remains constant at 2500 cm3. Gauge pressure of air to which the ball must have been originally inflated so that it would equal 1 bar gauge at the stadium is _
1) 2.23 bar
2) 1.94 bar
3) 1.07 bar
4) 1 bar

5 - The engine oil at 150 °C is cooled to 80 °C in a parallel flow heat exchanger by water entering at 25 °C and leaving at 60 °C. The exchanger effectiveness will be _
1) 0.36
2) 0.46
3) 0.56
4) 0.66

6 - The atomic packing factor is the highest in which of the following cubic lattice system?
1) Simple Cubic
2) Body Centered Cubic (BCC)
3) Face Centered Cubic (FCC)
4) Diamond Cubic
Correct Answer: Face Centered Cubic (FCC)

7 - If a mass of moist air in an airtight vessel is heated to a higher temperature, then _
1) specific humidity of the air increases
2) specific humidity of the air decreases
3) relative humidity of the air increases
4) relative humidity of the air decreases
Correct Answer: relative humidity of the air decreases

8 - In a vapour compression refrigeration system, liquid to suction heat exchanger is used to _
1) keep the COP constant
2) prevent the liquid refrigerant from entering the compressor
3) sub-cool the liquid refrigerant leaving the condenser
4) sub-cool the vapour refrigerant from the evaporator
Correct Answer: sub-cool the liquid refrigerant leaving the condenser

9 - A right-circular cylinder open at top is filled with water and rotated about its vertical axis at such speed that half the water spills out. What is the value of pressure at centre of the bottom?
1) One half its value when cylinder was full
2) One fourth its value when cylinder was full
3) Zero
4) Insufficient data

10 - The valves mounted on the boilers which change the direction of flow of steam by 90° and valves fitted in the pipelines which allow the steam in the same direction are respectively called as _
1) Stop valves and junction valves
2) Junction valves and stop valves
3) Junction valves and safety valves
4) Feed safety valves and stop valves
Correct Answer: Junction valves and stop valves

11 - Which of the following are boiler mountings and not boiler accessories ?
A] Pressure gauge
B] Air preheater
C] Superheated _
1) B and C only
2) A only
3) A, B and C
4) A and C only

12 - Entropy is a measure of _
1) Reversible heat transfer
2) System efficiency
3) Degree of randomness
4) System temperature

13 - At a point on a streamline, the velocity is 3 m/sec and the radius of curvature is 9 m. If the rate of increase of velocity along the streamline at this point is 1/3 m/sec/m, then the total acceleration at this point would be _
1) 1 m/sec2
2) 3 m/sec2
3) 1/3 m/sec2
4) √2 m/sec2

14 - Which of the following statements is correct regarding an impulse turbine?
1) The steam is initially compressed in a nozzle from low pressure to high pressure.
2) The steam is initially expanded in a nozzle from low pressure to high pressure.
3) The steam is initially compressed in a nozzle from high pressure to low pressure.
4) The steam is initially expanded in a nozzle from high pressure to low pressure.
Correct Answer: The steam is initially expanded in a nozzle from high pressure to low pressure.

15 - A draft tube is used with _
1) impulse turbine
2) Pelton wheel turbine
3) reaction turbines
4) axial turbine pumps

16 - Gibbs free energy is considered at which one of the following condition?
1) Isothermal, isochoric
2) Isobaric, isochoric
3) Isothermal, isobaric
4) None of these

17 - In vapour absorption refrigeration systems, which of the following fluids are commonly used?
1) air and water
2) sulphur dioxide and water
3) ammonia and water
4) freon and water

18 - In a cross compound steam engine _
1) one high and one low pressure cylinder are set side by side, driving the same shaft, cranks being set 90° apart
2) two cylinders are centred on the same piston rod, the 1.p. cylinder being placed nearest the crankshaft
3) two cylinders are set at 90°, usually to save floor space
4) None of these
Correct Answer: two cylinders are centred on the same piston rod, the 1.p. cylinder being placed nearest the crankshaft

19 - Which of the following is expected to have highest thermal conductivity?
1) steam
2) solid ice
3) melting ice
4) water

20 - For Newtonian fluid behaviour, the shear stress exerted by the fluid is equal to the _
1) Fluid viscosity divided by the velocity gradient parallel to the direction of shear.
2) Fluid viscosity divided by the velocity gradient perpendicular to the direction of shear.
3) Product of the fluid viscosity and the velocity gradient parallel to the direction of shear.
4) Product of the fluid viscosity and the velocity gradient perpendicular to the direction of shear.
Correct Answer: Product of the fluid viscosity and the velocity gradient perpendicular to the direction of shear.

21 - Which of the following are the advantages of impulse turbine over reaction turbines ?
A. Occupies less space per unit power.
B. Compounding is not necessary for speed reduction as the rotor speeds are usually low.
C. Suitable for high power generation.
Options:
1) B and C only
2) A only
3) C only
4) A and C only
Correct Answer: B and C only

22 - The compressors used in a gas turbine are typically of which type?
1) Centrifugal
2) Centripetal
3) Reciprocating
4) Axial

23 - A reversible thermodynamic cycle containing only three processes and producing work is to be constructed. The constraints are
A. there must be one isothermal process
B. there must be one isentropic process
C. maximum and minimum cycle pressures and the clearance volume are fixed, and
D. polytropic processes are not followed Then, the number of possible cycles is
Options:
1) 1
2) 2
3) 3
4) 4

24 - Which combination of the following statements is correct?
The incorporation of re-heater in a steam power plant
A. Always increases the thermal efficiency of the plant
B. Always increases the dryness fraction of steam at condenser inlet
C. Always increases the main temperature of heat addition
D. Always increases the specific work output
Options:
1) A and D only
2) B and D only
3) A, C and D only
4) A, B, C and D
Correct Answer: A, B, C and D

25 - The amount of heat required to raise the temperature of 1 kg of water from 0°C to the saturation temperature Ts °C at a given constant pressure is defined as _
1) Superheat
2) Entropy
3) Latent heat
4) Sensible heat

26 - Which turbine is also called as the propeller turbine?
1) Kaplan turbine
2) Francis turbine
3) Pelton wheel
4) Thompson turbine

27 - According to Bernoulli's principle in fluid dynamics, for inviscid flow, increase in speed of fluid leads to which of the following?
1) Increase in pressure and/or increase in fluid's potential energy
2) Decrease in pressure and/or increase in fluid's potential energy
3) Increase in pressure and/or decrease in fluid's potential energy
4) Decrease in pressure and/or decrease in fluid's potential energy
Correct Answer: Decrease in pressure and/or decrease in fluid's potential energy

28 - The material commonly used for air craft gas turbine is _
1) stainless steel
2) high alloy steel
3) duralumin
4) titanium

29 - The enthalpy of steam is defined as _
1) Difference of internal energy and product of pressure and volume.
2) Product of internal energy and pressure.
3) Sum of internal energy and product of pressure and volume.
4) Amount of heat change divided by the absolute temperature.
Correct Answer: Sum of internal energy and product of pressure and volume.

30 - What are the advantages of water tube boilers over fire tube boilers?
A. Steam at higher pressures can be produced.
B. More effective heat transfer.
C. Sediment deposition is more.
Options:
1) A only
2) A and C only
3) A, B and C
4) A and B only
Correct Answer: A and B only

31 - What is the state, in which none of the properties of the system change with time, known as?
3) Dynamic
4) Quasistatic

32 - The rate of heat transfer across any plane normal to the x-direction is proportional to the wall area and the temperature gradient in the x-direction. This statement is also referred to as _
1) Second Law of Thermodynamics
2) Kelvin's Law
3) Third Law of Thermodynamics
4) Fourier's Law

33 - The difference of absolute pressure and local atmospheric pressure is known as _
1) Negative pressure
2) Positive pressure
3) Gauge pressure
4) Hydraulic pressure

34 - The sum of pressure head and elevation head is known as _

35 - Specific gravity is defined as the ratio of density of fluid and density of water at which temperature (in °C)?
1) 0
2) 100
3) 4
4) It is not dependent on temperature

36 - The critical temperature of a pure substance is defined as _
1) The minimum temperature at which solid and liquid phases can coexist in equilibrium.
2) The maximum temperature at which solid and liquid phases can coexist in equilibrium.
3) The minimum temperature at which vapour and liquid phases can coexist in equilibrium.
4) The maximum temperature at which vapour and liquid phases can coexist in equilibrium.
Correct Answer: The maximum temperature at which vapour and liquid phases can coexist in equilibrium.

37 - Which of the following is the correct expression for the maximum thermal efficiency (η) of a system undergoing a reversible power cycle while operating between thermal reservoirs at temperatures Tc and Th
1) η = Tc/Th
2) η = Th/Tc-1
3) η = 1-Tc/Th
4) η = 1

38 - In actual refrigeration systems, the compressor handles vapour only. What is this process commonly referred to as _
1) Gas compression
2) Phase compression
3) Dry compression
4) Wet compression

39 - Property of a fluid at zero temperature is referred to as _
1) Stagnation property
2) Standard property
3) Simple property
4) None of these

40 - Falling drops of water become spheres due to the property of _
2) cohesion
3) surface tension
4) viscosity

41 - Fluid flow in a straight circular pipe is typically laminar in nature when the Reynolds number is _
1) Less than 2300
2) Less than 4000
3) More than 2300
4) More than 4000

42 - The reduction in fluid pressure that results when a fluid flows through a constricted section of a pipe is known as _
1) Orifice effect
2) Bernoulli's principle
3) Secondary flow
4) Venturi effect

43 - The increase in pressure _
1) lowers the boiling point of a liquid
2) raises the boiling point of a liquid
3) does not affect the boiling point of a liquid
4) reduces its volume
Correct Answer: raises the boiling point of a liquid

44 - The overall efficiency of thermal power plant is _
1) Boiler efficiency, turbine efficiency and generator efficiency
2) Boiler efficiency, turbine efficiency, generator efficiency and gas cycle efficiency
3) Carnot cycle efficiency
4) Regenerative cycle efficiency
Correct Answer: Boiler efficiency, turbine efficiency and generator efficiency

45 - Heat transfer by radiation mainly depends upon _
1) its temperature
2) nature of the body
3) kind and extent of its surface
4) All optons are correct
Correct Answer: All optons are correct

46 - Thermal diffusivity is _
1) a dimensionless parameter
2) function of temperature
3) used as mathematical model
4) a physical property of the material
Correct Answer: a physical property of the material

47 - For a compressible flow, Mach Number (M) is given by which of the following expression? where v = velocity of fluid in compressible flow c = speed of sound in air
1) M = v/√c
2) M = c/v
3) M = v/c
4) M = v/c2

48 - Which type of forces dominates a fluid flow with a very high Reynolds Number (Re ≈ 10000)?
1) Inertial
2) Viscous
3) Reaction
4) Divergent