Test: Thermodynamics Level - 1

# Test: Thermodynamics Level - 1 - Mechanical Engineering

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## 25 Questions MCQ Test Mechanical Engineering SSC JE (Technical) - Test: Thermodynamics Level - 1

Test: Thermodynamics Level - 1 for Mechanical Engineering 2023 is part of Mechanical Engineering SSC JE (Technical) preparation. The Test: Thermodynamics Level - 1 questions and answers have been prepared according to the Mechanical Engineering exam syllabus.The Test: Thermodynamics Level - 1 MCQs are made for Mechanical Engineering 2023 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Thermodynamics Level - 1 below.
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Test: Thermodynamics Level - 1 - Question 1

### The unit of power in S.I. units is

Detailed Solution for Test: Thermodynamics Level - 1 - Question 1

Power is measured in Watts.

Test: Thermodynamics Level - 1 - Question 2

### Work done in a free expansion process is

Detailed Solution for Test: Thermodynamics Level - 1 - Question 2

During free expansion, no work is done by the gas. The gas goes through states of no thermodynamic equilibrium before reaching its final state, which implies that one cannot define thermodynamic parameters as values of the gas as a whole. So work done in a free expansion process is Zero.

Test: Thermodynamics Level - 1 - Question 3

### An open system is one in which

Detailed Solution for Test: Thermodynamics Level - 1 - Question 3

An open system is a system that freely exchanges energy and matter with its surroundings.

Test: Thermodynamics Level - 1 - Question 4

Which of the following variables controls the physical properties of a perfect gas

Detailed Solution for Test: Thermodynamics Level - 1 - Question 4

Perfect gas, also called ideal gas, a gas that conforms, in physical behaviour, to a particular, idealized relation between pressure, volume, and temperature called the general gas law. This law is a generalization containing both Boyle’s law and Charles’s law as special cases and states that for a specified quantity of gas, the product of the volume v and pressure p is proportional to the absolute temperature t; i.e., in equation form, pv = kt, in which k is a constant. Such a relation for a substance is called its equation of state and is sufficient to describe its gross behaviour.

Test: Thermodynamics Level - 1 - Question 5

Which of the following laws is applicable for the behaviour of a perfect gas

Detailed Solution for Test: Thermodynamics Level - 1 - Question 5

Boyle's Law

a law stating that the pressure of a given mass of an ideal gas is inversely proportional to its volume at a constant temperature.

Charle's Law

a law stating that the volume of an ideal gas at constant pressure is directly proportional to the absolute temperature.

Gay-Lussac's Law

law states that the pressure of a given mass of gas varies directly with the absolute temperature of the gas, when the volume is kept constant.

Test: Thermodynamics Level - 1 - Question 6

According to kinetic theory of gases, the absolute zero temperature is attained when

Detailed Solution for Test: Thermodynamics Level - 1 - Question 6

The average kinetic energy of gas molecules is directly proportional to absolute temperature only; this implies that all molecular motion ceases if the temperature is reduced to absolute zero.

Test: Thermodynamics Level - 1 - Question 7

According to Gay-Lussac law for a perfect gas, the absolute pressure of given mass varies directly as

Detailed Solution for Test: Thermodynamics Level - 1 - Question 7

Gay-Lussac's Law

Tlaw states that the pressure of a given mass of gas varies directly with the absolute temperature of the gas, when the volume is kept constant.

Test: Thermodynamics Level - 1 - Question 8

Gas laws are applicable to

Detailed Solution for Test: Thermodynamics Level - 1 - Question 8

Because density of gas and vapour are diferent

Test: Thermodynamics Level - 1 - Question 9

According to Dalton's law the total pressure of the mixture of gases is equal to

Detailed Solution for Test: Thermodynamics Level - 1 - Question 9

Dalton's law (also called Dalton's law of partial pressures) states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases.

Test: Thermodynamics Level - 1 - Question 10

A closed system is one in which

Detailed Solution for Test: Thermodynamics Level - 1 - Question 10

In nonrelativistic classical mechanics, a closed system is a physical system that doesn't exchange any matter with its surroundings, and isn't subject to any net force whose source is external to the system. A closed system in classical mechanics would be considered an isolated system in thermodynamics.

Test: Thermodynamics Level - 1 - Question 11

Superheated vapour behaves

Detailed Solution for Test: Thermodynamics Level - 1 - Question 11
Explanation:
Superheated vapor refers to a state where a substance is heated beyond its boiling point while maintaining its gaseous form. In this state, the vapor does not contain any liquid droplets and is considered to be in a supercritical state.
Here is a detailed explanation of why superheated vapor behaves approximately as a gas:
1. Definition of a gas:
- A gas is a state of matter where particles are widely spread apart and move freely in all directions.
- It does not have a definite shape or volume.
2. Characteristics of superheated vapor:
- Superheated vapor is a gaseous phase of a substance that has been heated above its boiling point.
- It does not contain any liquid droplets.
- The particles in superheated vapor have high kinetic energy and move rapidly.
- The vapor molecules are widely spread apart, similar to a gas.
3. Comparison between superheated vapor and gas:
- Superheated vapor behaves similarly to a gas because both have particles that are widely spread apart and move freely.
- Both superheated vapor and gas do not have a definite shape or volume.
- The behavior of superheated vapor is often approximated to that of a gas due to its similarities in particle movement and distribution.
4. Differences between superheated vapor and steam:
- Steam refers to the gaseous phase of water at or below its boiling point.
- Steam can contain liquid droplets due to condensation or partial vaporization.
- Superheated vapor, on the other hand, does not contain any liquid droplets and is in a more energetic state compared to steam.
In conclusion, superheated vapor behaves approximately as a gas because its particles are widely spread apart, move freely, and do not have a definite shape or volume. However, it is important to note that superheated vapor is a distinct state of matter and should not be confused with steam, which can contain liquid droplets.
Test: Thermodynamics Level - 1 - Question 12

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

Detailed Solution for Test: Thermodynamics Level - 1 - Question 12

PVγ = constant

is the expression for Polytropic Process where γ is a constant

If γ = 1, PV = constant which is only true for an isothermal process.

Hence option C is correct.

Test: Thermodynamics Level - 1 - Question 13

A piston cylinder contains 0.5 kg of air at 500 kPa and 500 K. The air expands in a process so pressure is linearly decreasing with volume to a final state of 100 kPa and 300 K. Find the work in the process.

Detailed Solution for Test: Thermodynamics Level - 1 - Question 13 Test: Thermodynamics Level - 1 - Question 14

Gases have

Detailed Solution for Test: Thermodynamics Level - 1 - Question 14

The specific heats of gases are given as Cp and Cv at constant pressure and constant volume respectively while solids and liquids are having only single value for specific heat.

Test: Thermodynamics Level - 1 - Question 15

Detailed Solution for Test: Thermodynamics Level - 1 - Question 15

Avogadro's law states that, "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules." For a given mass of an ideal gas, the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are constant.

Test: Thermodynamics Level - 1 - Question 16

The pressure of a gas in terms of its mean kinetic energy per unit volume E is equal to

Detailed Solution for Test: Thermodynamics Level - 1 - Question 16

Pressure in terms of kinetic energy per unit volume:- The pressure of a gas is equal to two-third of kinetic energy per unit volume of the gas.

P = 2E/3

Test: Thermodynamics Level - 1 - Question 17

Kinetic energy of the molecules in terms of absolute temperature (T) is proportional to

Detailed Solution for Test: Thermodynamics Level - 1 - Question 17

Kinetic energy of molecules is the form of internal energy in a closed vessel, and internal energy is the function of temperature so kinetic energy of molecules is proportional to absolute temprature

Test: Thermodynamics Level - 1 - Question 18

One kg of carbon monoxide requires __________ kg of oxygen to produce 11/7 kg of carbon dioxide gas.

Detailed Solution for Test: Thermodynamics Level - 1 - Question 18

2CO + O2 = 2 CO2
(2*28) (16*2) (2*44)

=56 kg =32 kg =88 kg

=1 kg =32/56 kg =88/56 kg

=1 kg =4/7 kg =11/7 kg

That is 4/7 kg of O2 is required for preaparing 11/7 kg of CO2 from 1 kg CO.

Test: Thermodynamics Level - 1 - Question 19

Absolute zero pressure will occur

Detailed Solution for Test: Thermodynamics Level - 1 - Question 19

The absolute zero pressure will be when the molecular momentum of the system becomes zero. ... Thus, Pressure P = F/A = Rate of change of momentum/Area. Now when the ''rate of change of momentum' is zero, the above equation becomes: P = 0 / area = 0 which is the absolute zero pressure.

Test: Thermodynamics Level - 1 - Question 20

No liquid can exist as liquid at

Detailed Solution for Test: Thermodynamics Level - 1 - Question 20

Liquids are volatile. If taken to zero pressure which effectively means vacuum, in that case, it will boil and vapourise. While different liquids have different viscosity but eventually it will vapourise as there is no pressure to help it maintain the viscosity and surface tension. Water will vapourise much faster than say mercury.

Test: Thermodynamics Level - 1 - Question 21

The condition of perfect vacuum, i.e., absolute zero pressure can be attained at

Detailed Solution for Test: Thermodynamics Level - 1 - Question 21

The condition of perfect vacuum, i.e., absolute zero pressure can be attained at. a temperature of - 273.16°C. a temperature of 0°C.

Test: Thermodynamics Level - 1 - Question 22

Specific heat of air at constant pressure is equal to

Detailed Solution for Test: Thermodynamics Level - 1 - Question 22

For ordinary calculations - a value of specific heat cp = 1.0 kJ/kg K (equal to kJ/kg oC) or 0.24 Btu(IT)/lb °F - is normally accurate enough

Test: Thermodynamics Level - 1 - Question 23

Characteristic gas constant of a gas is equal to

Detailed Solution for Test: Thermodynamics Level - 1 - Question 23

We know by the formula Cp - Cv = R

Test: Thermodynamics Level - 1 - Question 24

The behaviour of gases can be fully determined by

Detailed Solution for Test: Thermodynamics Level - 1 - Question 24

Avogadro's Law states that equal volumes of all ideal gases (at the same temperature and pressure) contain the same number of molecules.

Boyle's Law states that equal pressure is inversely proportional to volume (when temperature is constant).

Charles's Law states that volume is proportional to temperature (when pressure is constant). Remember that temperature must be measured in Kelvin.

Gay-Lussac's Law states that pressure is proportional to temperature (when volume is constant).

Test: Thermodynamics Level - 1 - Question 25

To convert volumetric analysis to gravimetric analysis, the relative volume of each constituent of the flue gases is

Detailed Solution for Test: Thermodynamics Level - 1 - Question 25

To convert volumetric analysis to gravitational analysis, relative volume of each constituent of flue gases is multiplied by its molecular weight.

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