## MCQ on gas laws

** MCQ General Knowledge on Behavior of Gas Boyle’s Law, Charles’s Law Avogadro’s Law Objective short Questions and Answers** for class 9 10 and aspirants who are preparing for competitive govt job examinations like SSC, CGL, MTS, IAS, UPSC, Railway, Banking, Defence, Police CDS, etc..

**Q.1 The constant quantity of Boyle’s Law is**

A: Only mass of the gas

B: Only temperature of a gas

C: Mass and Pressure of a gas

D: Mass and temperature of a gas

Answer

D: Mass and temperature of a gas.

**Q.2 Let the pressure P and volume V for a certain gas. If the pressure is increased by 25% at a constant temperature, then what would be the volume of the gas?**

A: 0.6V

B: 0.75V

C: 0.8V

D: 0.85V

Answer

0.8V

**Q.3 What is the nature of the pressure-volume (P-V) graph in Boyle’s Law?**

A: Straight Line;

B: Circle:

C: Elliptical;

D: Rectangular Hyperbola:

Answer

Rectangular Hyperbola.

**Q.4 What is the nature of the pressure-volume vs Pressure (PV vs P) graph in Boyle’s Law?**

A: Straight Line parallel to P axis;

B: Straight line parallel to PV axis:

C: Elliptical;

D: Hyperbola:

Answer:

Straight-line parallel to the P axis.

**Q.5 The unit of pressure in the SI system is-**

A: N

B: N-m

C: N-m^{2}

D: N/m^{2}

Answer:

N/m^{2}

**Q.6 1 m3 = ______ cm3**

A: 100

B: 10^{3}

C:10^{5}

D: 10^{6}

Answer

D: 10^{6}

**Q.7 If the pressure of a certain amount of gas is reduced to 1/4 ^{th} of its initial pressure at a fixed temperature, then what would be its final volume?**

A: 2 times

B: 3 times

C: 4 times

D: 6 times

Answer

C: 4 times

**Q.8 If the pressure is increased by 2 times of a certain amount of gas at a fixed temperature, then what would be its final volume?**

A: Double

B: One half

C: Tripple

D: One fourth

Answer

B: One half

**Q.9 Suppose, at for a gas having constant mass the volume is V _{0} at temperature 0 ^{o}C. What would be its final volume at 100 ^{o}C if the pressure remains constant?**

A: (293/273)V_{0}

B:(283/273)V_{0}

C: (303/273)V_{0}

D: (373/273)V_{0}

Answer

(303/273)V_{0}

**Q.10 For a given mass of an ideal gas at constant pressure, the graph V – t (t in Celcius scale), intersect the temperature axis at –**

A: – 273 ^{o}C

B: 0 ^{o}C

C: 273 ^{o}C

D: Do not intersect.

Answer

A: – 273 ^{o}C

**Q.11 In which scale of temperature, the temperature can not be negative?**

A: Celcius Scale

B: Fernheight Scale

C: Absolute Scale

D: All of the above

Answer

C: Absolute Scale

**Q.12 The Freezing point of water in absolute scale is-**

A: 0 K

B: 273 K

C: 212 K

D: None of the above;

Answer

B: 273 K

**Q.13 If the temperature is increased from 0 ^{o}C to 30 ^{o}C at a constant pressure of gas having fixed mass, then the ratio of initial and final volume will be –**

A: 91 : 101

B: 91 : 100

C: 91 : 111

D: 91 : 121

Answer

A: 91 : 101

**Q.14 The constant quantity(s) in Charle’s Law is (are)-**

A: Temperature

B: Volume

C: Pressure and Mass of gas

D: Temperature and Mass of gas

Answer

Pressure and Mass of a gas.

**Q.15 The nature of the V-t (t in Celcius scale) graph in Charle’s law is-**

A: Straight line

B: Circle

C: Parabola

D: Hyperbola

Answer

Straight line

**Q.16 At which temperature the volume of gas reduces to Zero?**

A: 0 K

B: 0 ^{o}C

C: 273 ^{o}C

D: 273 K

Answer

A: 0 K

**Q.17 Which Scientist discovered the absolute scale of temperature?**

A: Charles

B: Boyle

C: Kelvin

D: Gay-Lussac.

Answer

Kelvin

**Q.18 At which temperature the real gas behaves as an ideal gas?**

A: At high pressure and low temperature;

B: At low-pressure and high temperature;

C: At low pressure and low temperature;

D: AT high pressure and high temperature;

Answer

B: At high temperature and low pressure;

**Q.19 The molar mass of water is –**

A: 16 g

B: 20 g

C: 18 g

D: 44 g

Answer

C: 18 g

**Q.20 The mass of 5 mol of Hydrogen gas is-**

A: 5 g

B: 10 g

C: 18 g

D: 27 g

Answer

B: 10 g

**Q.21 In the case of collision of two gas molecule of an ideal gas –**

A: The linear momentum is conserved only;

B: The kinetic energy is conserved only;

C: Linear momentum and kinetic energy both conserve;

D: Linear momentum and kinetic energy both are not conserved;

Answer

C: Linear momentum and kinetic energy both are conserved.

**Q.22 The energy of the molecules of an ideal gas is –**

A: Only potential energy;

B: Only kinetic energy;

C: Kinetic energy + potential energy;

D: Kinetic energy – potential energy;

Answer

B: Only kinetic energy;

**Q.23 Which is the Ideal Gas Equation from the following?**

A: PV = mc^{2};

B: PV = mgh;

C: PV = nRT;

D: PV = mSt;

Answer

C: PV = nRT;

**Q.24 Which is the constant quantity in Idial Gas Equation?**

A: Pressure P

B: Volume V

C: R

D: Temperature

Answer

C: R

**Q.25 The value of Universal Gas Constant in CGS unit is –**

A: 8.31 * 10^{6}

B: 8.31 * 10^{7}

C: 8.31 * 10^{8 }

D: 8.31 * 10^{9}

Answer

B: B: 8.31 * 10^{7}

**Q.26 The dimension of the universal gas constant is –**

A: M L^{2} T^{-1} N^{-1}

B: M L^{-1} T^{-1} N^{-2}K^{-1}

C: M L^{2} T^{-1} N^{-2} K

D: M L^{-1} T^{-2} N^{-1 }K^{-1}

Answer

D: M L^{-1} T^{-2} N^{-1 }K^{-1}

**Q.27 According to the kinetic theory of gas, at which temperature the kinetic energy of a molecule of an ideal gas becomes zero?**

A: — 273 ^{o}C

B: 0 ^{o}C

C: – 100 ^{o}C

D: 273 K

Answer

A: — 273 ^{o}C

**Q.28 84 g of N _{2} = ______ g N_{2}.**

A: 1 g

B: 2 g

C: 3 g

D: 4 g

Answer

C: 3 g

**Q.29 Which of the following has the largest volume?**2 g of Hydrogen Gas, 28 g of Nitrogen Gas, 44 g of CO

_{2}gas.

A: 2 g of Hydrogen Gas

B: 28 g of Nitrogen Gas

C: 44 g of CO_{2} gas

D: All gasses have the same volume.

Answer

D: All the gas has the same volume.

**Q.30 How many atoms are there in 1 mol of CO _{2} gas if the Avogadro number in N?**

A: N

B: 2N

C: 3N

D: 4N

Answer

C: 3N

**Q.31 If the mass of 11.2 L of CO _{2} is 22g, then what is its atomic mass?**

A: 22

B: 44:

C: 88

D: 11

Answer

B: 44

**Q.32 The mass of an O _{2} molecule is –**

A: 5.31 * 10^{-23}g

B: 10.62 * 10^{-23}

C: 15.93 * 10^{-23}

D: 2.65 * 10^{-23}

Answer

5.31 * 10^{-23}g

**Q.33 The number of molecules of 7g of N _{2} gas is-**

A: 22.044 * 10^{23}

B: 1.506 * 10^{23}

C: 3.011 * 10^{23}

D: 6.022 * 10^{23}

Answer

1.506 * 10^{23}

**Q.34 The volume of 2.2 g CO _{2} at 27 ^{o}C and 570 mm pressure is –**

A: 4.83 L

B: 0.82 L

C: 3.82 L

D: 1.64 L

Answer

D: 1.64 L

**Q.35 At which condition the real gas deviated from the ideal gas?**

A: At low temperature and low pressure

B: At Low pressure and high temperature;

C: At high pressure and low temperature;

D: At high pressure and high temperature;

Answer

At low temperature and high pressure.

**Q.36 The state of the equation for 7g of Oxygen gas is _**

A: PV = 7RT

B: PV = (32/7)RT

C: PV = (7/32)RT

D: PV = 32RT

Answer

C: PV = (7/32)RT

**Q.37 If the pressure of a certain amount of gas is increased at a constant temperature, the density of the gas is –**

A: Remain Constant;

B: Decreased;

C: Increased;

D: Can not be determined;

Answer

Increased

**Q.38 What would be the volume of 22g of Carbon dioxide at STP?**

A: 11.2 L

B: 1.12 L

C: 22.4 L

D: 2.24 L

Answer

11.2 L

**Q.39 The molar volume of any gas at STP is –**

A: 22.4 L

B: 2.24 L

C: 44 L

D: 24.2 L

Answer

22.4 L