Mechanical Engineering Mcqs Part 2

Most of the NTS Sample Papers consist of NTS MCQS having multiple choice questions (MCQs) like MCQS of Computer, MCQS of Islamiat, MCQS of Chemistry, NTS English MCQS, and NTS General Knowledge MCQS. Mechanical Engineering Mcqs Part 2 given below

 

 

Mechanical Engineering Mcqs Part 2

 

36. Gases have

(a) only one value of specific heat

(b) two values of specific heat

(c) three values of specific heat

(d) no value of specific heat

(e) under some conditions one value and sometimes two values of specific heat.

Ans: b

  1. According to Avogadro’s Hypothesis

(a) the molecular weights of all the perfect gases occupy the same volume under same

conditions of pressure and temperature

(b) the sum of partial pressure of mixture of two gases is sum of the two

(c) product of the gas constant and the molecular weight of an ideal gas is constant

(d) gases have two values of specific heat

(e) all systems can be regarded as closed systems.

Ans: a

  1. Extensive property of a system is one whose value

(a) depends on the mass of the system like volume

(b) does not depend on the mass of the system, like temperature, pressure, etc.

(c) is not dependent on the path followed but on the state

(d) is dependent on the path followed and not on the state

(e) is always constant.

Ans: a

  1. Work done in a free expansion process is

(a) + ve

(b) -ve

(c) zero

(d) maximum

(e) minimum.

Ans: c

  1. The statement that molecular weights of all gases occupy the same volume is

known as

(a) Avogadro’s hypothesis

(b) Dalton’s law

(c) Gas law

(d) Law of thermodynamics

(e) Joule’s law.

Ans: a

  1. To convert volumetric analysis to gravimetric analysis, the relative volume of each

constituent of the flue gases is

(a) divided by its molecular weight

(b) multiplied by its molecular weight

(c) multiplied by its density

(d) multiplied by its specific weight

(e) divided by its specific weight.

Ans: b

  1. If a gas is heated against a pressure, keeping the volume constant, then work

done will be equal to

 

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(a) + v

(b) – ve

(c) zero

(d) pressure x volume

(e) anywhere between zero and infinity.

Ans: c

  1. An isolated system is one in which

(a) mass does not cross boundaries of the system, though energy may do so

(b) neither mass nor energy crosses the boundaries of the system

(c) both energy and mass cross the boundaries of the system

(d) mass crosses the boundary but not the energy

(e) thermodynamic reactions do not occur.

Ans: b

  1. Properties of substances like pressure, temperature and density, in thermodynamic

coordinates are

(a) path functions

(b) point functions

(c) cyclic functions

(d) real functions

(e) thermodynamic functions.

Ans: b

  1. Which of the following quantities is not the property of the system

(a) pressure

(b) temperature

(c) specific volume

(d) heat

(e) density.

Ans: d

  1. According to Avogadro’s law, for a given pressure and temperature, each molecule

of a gas

(a) occupies volume proportional to its molecular weight

(b) occupies volume proportional to its specific weight

(c) occupies volume inversely proportional to its molecular weight

(d) occupies volume inversely proportional to its specific weight

(e) occupies same volume.

Ans: e

  1. Mixture of ice and water form a

(a) closed system

(b) open system

(c) isolated system

(d) heterogeneous system

(e) thermodynamic system.

Ans: d

  1. Which of the following is the property of a system

 

(a)pressure and temperature

(b)internal energy

(c) volume and density

(d) enthalpy and entropy

(e) all of the above.

Ans: e

  1. On weight basis, air contains following parts of oxygen

(a) 21

(b) 23

(c) 25

(d) 73

(e) 79.

Ans: b

  1. Which of the following is not the intensive property

(a) pressure

(b) temperature

(c) density

(d) heat

(e) specific volume.

Ans: d

  1. Which of the following items is not a path function

(a) heat

(b) work

(c) kinetic energy

(d) vdp

(e) thermal conductivity.

Ans: e

  1. Work done in an adiabatic process between a given pair of end states depends on

(a) the end states only

(b) particular adiabatic process

(c) the value of index n

(d) the value of heat transferred

(e) mass of the system.

Ans: a

  1. Heat and work are

(a) point functions

(b) system properties

(c) path functions

(d) intensive properties

(e) extensive properties.

Ans: c

  1. Which of the following parameters is constant for a mole for most of the gases at a

given temperature and pressure

(a) enthalpy

(b) volume

(c) mass

(d) entropy

(e) specific volume.

Ans: b

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  1. The value of n = 1 in the polytropic process indicates it to be

(a) reversible process

(b) isothermal process

(c) adiabatic process

(d) irreversible process

(e) free expansion process.

Ans: b

  1. Solids and liquids have

(a) one value of specific heat (ft) two values of specific heat

(c) three values of specific heat

(d) no value of specific heat

(e) one value under some conditions and two values under other conditions.

Ans: a

  1. A perfect gas at 27°C is heated at constant pressure till its volume is double. The

final temperature is

(a) 54°C

(b) 327°C

(c) 108°C

(d) 654°C

(e) 600°C

Ans: b

  1. Curve A in Fig. 1.1 compared to curves B and C shows the following type of

expansion

(a) pV”=C

(b) isothermal

(c) adiabatic

(d) free expansion

(e) throttling.

Ans: b

  1. If value of n is infinitely large in a polytropic process pV” = C, then the process is

known as constant

(a) volume

(b) pressure

(c) temperature

(d) enthalpy

(e) entropy.

Ans: a

  1. The index of compression n tends to reach ratio of specific heats y when

(a) flow is uniform and steady

(b) process is isentropic

(c) process is isothermal

(d) process is isentropic and specific heat does not change with temperature

(e) process is isentropic and specific heat changes with temperature.

Ans: d

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  1. Change in enthalpy of a system is the heat supplied at

(a) constant pressure

(b) constant temperature

(c) constant volume

(d) constant entropy

(e) N.T.P. condition.

Ans: a

  1. The term N.T.P. stands for

(a) nominal temperature and pressure

(b) natural temperature and pressure

(c) normal temperature and pressure

(d) normal thermodynamic practice

(e) normal thermodynamic pressure.

Ans: c

  1. A heat exchange process in which the product of pressure and volume remains

constant is known as

(a) heat exchange process

(b) throttling process

(c) isentropic process

(d) adiabatic process

(e) hyperbolic process.

Ans: e

  1. In an isothermal process, the internal energy of gas molecules

(a) increases

(b) decreases

(c) remains constant

(d) may increase/decrease depending on the properties of gas

(e) shows unpredictable behaviour.

Ans: c

  1. Zeroth law of thermodynamics

(a) deals with conversion of mass and energy

(b) deals with reversibility and irreversibility of process

(c) states that if two systems are both in equilibrium with a third system, they are in

thermal equilibrium with each other

(d) deals with heat engines

(e) does not exist.

Ans: c

  1. If a certain amount of dry ice is mixed with same amount of water at 80°C, the

final temperature of mixture will be

 

(a) 80°C

(b) 0°C

(c) 40°C

(d) 20°C

(e) 60°C.

Ans: b

  1. The basis for measuring thermodynamic property of temperature is given by

(a) zeroth law of thermodynamics

(b) first law of thermodynamics

(c) second law of thermodynamics

(d) third law of thermodynamics

(e) Avogadro’s hypothesis.

Ans: a

  1. One watt is equal to

(a) 1 Nm/s

(b) 1 N/mt

(c) 1 Nm/hr

(d) 1 kNm/hr

(e) 1 kNm/mt.

Ans: a

  1. Work done is zero for the following process

(a) constant volume

(b) free expansion

(c) throttling

(d) all Of the above

(e) none of the above.

Ans: d

  1. For which of the following substances, the gas laws can be used with minimum

error

(a) dry steam

(b) wet steam

(c) saturated steam

(d) superheated steam

(e) steam at atmospheric pressure.

Ans: d

  1. In a non-flow reversible process for which p = (- 3V+ 15) x 105N/m2,V changes

from 1 m to 2 m3. The work done will be about

(a) 100 xlOO5 joules

(b) lxlO5 joules

(c) 10 xlO5 joules

(d) 10 xlO5 kilo joules

(e) 10xl04ki\ojoules.

Ans: c

  1. The value of the product of molecular weight and the gas characteristic constant

for all the gases in M.K.S. unit is

(a) 29.27 kgfm/mol°K

(b) 8314kgfm/mol°K

(c) 848kgfm/mol°K

(d) 427kgfm/mol°K

(e) 735 kgfm/mol°K.

Ans: c

  1. On volume basis, air contains following parts of oxygen

(a) 21

(b) 23

(c) 25

(d) 77

(e) 79.

Ans: a

  1. Universal gas constant is defined as equal to product of the molecular weight of the

gas and

(a) specific heat at constant pressure

(b) specific heat at constant volume

(c) ratio of two specific heats

(d) gas constant

(e) unity.

Ans: d

  1. The value of the product of molecular weight and the gas characteristic constant

for all the gases in S.I. units is

(a) 29.27 J/kmol°K

(b) 83.14J/kmol°K

(c) 848J/kmol°K

(d) All J/kmol °K

(e) 735 J/kmol °K.

Ans: b

  1. For which of the following substances, the internal energy and enthalpy are the

functions of temperature only

(a) any gas

(b) saturated steam

(c) water

(d) perfect gas

(e) superheated steam.

Ans: d

  1. In a free expansion process

(a) work done is zero

(b) heat transfer is zero

(c) both (a) and (b) above

(d) work done is zero but heat increases

(e) work done is zero but heat decreases.

Ans: c

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  1. If a gas vapour is allowed to expand through a very minute aperture, then such a process is known as

(a) free expansion

(b) hyperbolic expansion

(c) adiabatic expansion

(d) parabolic expansion

(e) throttling.

Ans: e

  1. The specific heat of air increases with increase in

(a) temperature

(b) pressure

(c) both pressure and temperature

(d) variation of its constituents

(e) air flow

Ans: a

  1. If a fluid expands suddenly into vacuum through an orifice of large dimension, then

such a process is called

(a) free expansion

(b) hyperbolic expansion

(c) adiabatic expansion

(d) parabolic expansion

(e) throttling.

Ans: a

  1. Which of the following processes are thermodynamically reversible

(a) throttling

(b) free expansion

(c) constant volume and constant pressure

(d) hyperbolic and pV = C

(e) isothermal and adiabatic.

Ans: e

  1. Which of the following processes is irreversible process

(a) isothermal

(b) adiabatic

(c) throttling

(d) all of the above

(e) none of the above.

Ans: c

  1. In order that a cycle be reversible, following must be satisfied

(a) free expansion or friction resisted expansion/compression process should not be

encountered

(b) when heat is being absorbed, temperature of hot source and working sub¬stance

should be same

(c) when beat is being rejected, temperature of cold source and working sub-stance

should be same

(d) all of the above

(e) none of the above.

Ans: d

  1. For a thermodynamic process to be reversible, the temperature difference between

hot body and working substance should be

(a) zero

(b) minimum

(d) maximum

(d) infinity

(e) there is no such criterion.

Ans: a

  1. Minimum work in compressor is possible when the value of adiabatic index n is

equal to

(a) 0.75

(b) 1

(c) 1.27

(d) 1.35

(e) 2.

Ans: b

  1. Molecular volume of any perfect gas at 600 x 103 N/m2 and 27°C will be

(a) 4.17m3/kgmol

(b) 400 m3/kg mol

(c) 0.15 m3/kg mol

(d) 41.7 m3/kg mol

(e) 417m3/kgmol.

Ans: a

  1. A gas is compressed in a cylinder by a movable piston to a volume one-half its

original volume. During the process 300 kJ heat left the gas and internal energy

remained same. The work done on gas in Nm will be

(a) 300 Nm

(b) 300,000 Nm

(c) 30 Nm

(d) 3000 Nm

(e) 30,000 Nm.

Ans: b

  1. The more effective way of increasing efficiency of Carnot engine is to

(a) increase higher temperature

(b) decrease higher temperature

(c) increase lower temperature

(d) decrease lower temperature

(e) keep lower temperature constant.

Ans: d

  1. Entropy change depends on

(a) heat transfer

(b) mass transfer

(c) change of temperature

(d) thermodynamic state

(e) change of pressure and volume.

Ans: a

  1. For reversible adiabatic process, change in entropy is

(a) maximum

(b) minimum

(c) zero

(d) unpredictable

(e) negative.

Ans: c

  1. Isochoric process is one in which

(a) free expansion takes place

(b) very little mechanical work is done by the system

(c) no mechanical work is done by the system

(d) all parameters remain constant

(e) mass and energy transfer do not take place.

Ans: c

  1. According to first law of thermodynamics

(a) work done by a system is equal to heat transferred by the system

(b) total internal energy of a system during a process remains constant

(c) internal energy, enthalpy and entropy during a process remain constant

(d) total energy of a system remains constant

(e) entropy of a system remains constant.

Ans: d

  1. Energy can neither be created nor destroyed but can be converted from one form

to other is inferred from

(a) zeroth low of thermodynamic

(b) first law of thermodynamics

(c) second law to thermodynamics

(d) basic law of thermodynamics

(e) claussius statement.

Ans: b

  1. First law of thermodynamics furnishes the relationship between

(a) heat and work

(b) heat, work and properties of the system

(c) various properties of the system

(d) various thermodynamic processes

(e) heat and internal energy.

Ans: b

  1. Change in enthalpy in a closed system is equal to heat transferred if the reversible

process takes place at constant

(a) pressure

(b) temperature

(c) volume

(d) internal energy

(e) entropy.

Ans: a

  1. In an isothermal process, the internal energy

(a) increases

(b) decreases

(c) remains constant

(d) first increases and then decreases

(e) first decreases and then increases.

Ans: c

  1. Change in internal energy in a closed system is equal to heat transferred if the

reversible process takes place at constant

(a) pressure

(b) temperature

(c) volume

(d) internal energy

(e) entropy.

Ans: c

  1. According to first law of thermodynamics

(a) mass and energy are mutually convertible

(b) Carnot engine is most efficient

(c) heat and work are mutually convertible

(d) mass and light are mutually convertible

(e) heat flows from hot substance to cold substance.

Ans: c

  1. Total heat of a substance is also known as

(a) internal energy

(b) entropy

(c) thermal capacity

(d) enthalpy

(e) thermal conductance.

Ans: d

  1. First law of thermodynamics

(a) enables to determine change in internal energy of the system

(b) does not help to predict whether the system will or not undergo a change

(c) does not enable to determine change in entropy

(d) provides relationship between heat, work and internal energy

(e) all of the above.

Ans: e

  1. Addition of heat at constant pressure to a gas results in

(a) raising its temperature

(b) raising its pressure

(c) raising its volume

(d) raising its temperature and doing external work

(e) doing external work.

Ans: d

  1. Carnot cycle has maximum efficiency for

(a) reversible engine

(b) irreversible engine

(c) new engine

(d) petrol engine

(e) diesel engine.

Ans: a

  1. Measurement of temperature is based on

(a) thermodynamic properties

(b) zeroth law of thermodynamics

(c) first law of thermodynamics

(d) second law of thermodynamics

(e) joule’s law.

Ans: b

  1. Carnot cycle efficiency depends upon

(a) properties of the medium/substance used

(b) condition of engine

(c) working condition

(d) temperature range of operation

(e) effectiveness of insulating material around the engine.

Ans: d

  1. Carnot cycle efficiency is maximum when

(a) initial temperature is 0°K

(b) final temperature is 0°K

(c) difference between initial and final temperature is 0°K

(d) final temperature is 0°C

(e) initial temperature is minimum possible.

Ans: b

  1. An engine operates between temperatures of 900°Kandr2 and another engine

between T2 and 400°K For both to do equal work, value of T2 will be

(a) 650°K

(b) 600°K

(c) 625°K

(d) 700°K

(e) 750°K.

Ans: a

  1. If heat be exchanged in a reversible manner, which of the following property of

the working substance will change accordingly

(a) temperature

(b) enthalpy

 

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