WBBSE Solutions For Class 10 Physical Science And Environment Chapter 2 Behaviour Of Gases

WBBSE Class 10 Physical Science Question Answer In English

Chapter 2 Behaviour Of Gases Very Short Answer Type Questions

Question 1. Write the ideal gas equation for one gram-mole gas.
Answer: PV = RT.

Question 2. What is the value of absolute temperature in Fahrenheit scale?
Answer: (-) 459.4° F

Question 3. What is the SI unit of pressure?
Answer: The SI unit of pressure is Pascal.

Question 4. How is an atmosphere of gas determined?
Answer: the atmosphere of gas pressure is determined by Barometer invented by Torricelli.

Question 5. Give a mathematical expression of Boyle’s law.
Answer: V x P = Constant.

Question 6. Give a mathematical expression of Charles’s law.
Answer: \(\frac{\mathrm{V}}{\mathrm{T}}=\text { Constant. }\)

Question 7. What is meant by ideal gases?
Answer: Gases which obey Boyle’s law and Charle’s law at all pressure and temperature.

Read And Learn More: WBBSE Solutions For Class 10 Physical Science And Environment

Question 8. What is the effect of the withdrawal of heat from a gas at constant volume?
Answer: The temperature of the gas falls.

Question 9. What is Torr?
Answer: Torr is the unit of pressure used at high vacuum. 1 Torr 1 mm of Hg.

Question 10. Give a main property a gas.
Answer: Diffusion is a main property of a gas.

WB Class 10 Physical Science Question Answer

Question 11. What is Loschmidt’s number?
Answer: The number of molecules present in 1 ml. of gas or vapour at STP is known as the Loschmidt number.

Question 12. Is Charle’s law applicable to liquids?
Answer: Charle’s law is not applicable to liquids.

Question 13. What will be the volume of an ideal gas at absolute gas?
Answer: The volume, will be zero.

Question 14. What is the cause of the temperature of the gas?
Answer: Kinetic energy is possessed by gaseous molecules.

Question 15. Why are gaseous molecules always in incessant motion?
Answer: Because gaseous molecules have no mutual force of attraction.

Question 16. How does the volume of a gas change for each degree Celsius rise of temperature at constant pressure?
Answer: \(\frac{1}{273}\) of the volume of the gas at 0°C increases.

Question 17. What will happen when a gas-filled balloon is heated?
Answer: The balloon will burst as the supplied heat increases the volume of the gas inside the balloon.

Question 18. What are the variable quantities in Charle’s law?
Answer: In Charle’s law, the variable quantities are temperature and volume.

Question 19. What are the variable quantities in Boyle’s law?
Answer: In Boyle’s law, the variable quantities are pressure and volume.

14. What are the constant quantities in Charle’s law?
Answer: In Charle’s law, the constant quantities are the mass of the gas and pressure.

Physics Class 10 WBBSE Chapter 2 Behaviour Of Gases Fill In The Blanks

Question 1. The volume of a gas is zero at ________ temperature.
Answer: Absolute

Question 2. According to the kinetic theory of gases, the kinetic energy of gases is directly proportional to its ________.
Answer: absolute on Kelvin temperature.

Question 3. The law which describes the relationship between the volume and temperature of a gas at constant pressure is called _______.
Answer: Charle’s law.

Question 4. The scale of temperature with – 273°C as zero is called _________.
Answer: Absolute or Kelvin temperature scale.

WB Class 10 Physical Science Question Answer

Question 5. According to the kinetic theory of gases, a gas consists of discrete particles called _________.
Answer: molecules.

Question 6. Real gases do not behave like ideal gases because they have intermolecular _______ and the molecules do not have negligible volume.
Answer: attraction.

Question 7. Absolute scale reading = Celsius scale reading + _________.
Answer: 273.

Question 8. 330K ________ °C.
Answer: 57.

Question 9. The pressure of a gas is determined by _________.
Answer: Manometer.

Question 10. The value of normal pressure in the SI system is ________ pascal.
Answer: 1.013 × 10⁵.

Question 11. The boiling point of water is ________ Kelvin.
Answer: 273.

Question 12. At ________ °C, the gas molecules become motionless.
Answer: (-) 273.

Question 13. At constant temperature, the volume of a given mass of gas varies ________ as its pressure.
Answer: Inversely.

Question 14. For a given mass of a gas or vapour at a constant temperature, pressure ________ = constant.
Answer: Volume.

Question 15. The law of pressure is known as _________.
Answer: Regnault’s law.

Question 16. Any real gas becomes _______ before it reaches absolute zero.
Answer: Liquefied.

Question 17. P₁ V₁ = P₂ V₂ is related to ________.
Answer: Boyle’s law.

Question 18. The relation between pressure, temperature and density of a gas is _________.
Answer: \(\frac{\mathrm{P}}{\mathrm{DT}}=\text { constant }\)

Question 19. The boiling point of water on the Kelvin scale is _________.
Answer: 373 K.

Class 10 Physical Science WBBSE

Question 20. A constant temperature for a given volume of gas the product of its pressure and its volume is ________.
Answer: Constant.

Question 21. The value of absolute zero is ________ on the Celsius scale.
Answer: -273°C.

Question 22. The equation of ideal gas for a gram-moles is _________.
Answer: PV = nRT

Question 23. The volume of a given mass of gas varies directly as ________ temperature at constant pressure.
Answer: absolute.

Question 24. Gases like H₂ , O₂ , N₂ , Cl₂, etc. Which abey Boyle’s law and Charle’s law at low pressure and _______ temperature are called real gases.
Answer: high.

Question 25. The constant quantities in Boyle’s law are _______ and temperature.
Answer: mass.

Question 26. Gaseous molecules have no mutual force of _________ So they are always in an incessant motion.
Answer: Attraction.

Question 27. If heat is supplied to a gas, its molecules move with more ________ So the temperature of the gas rises.
Answer: energy.

Question 28. The normal temperature is taken as 0°C or _______ K and the normal pressure is taken as 76cm mercury or 1 atmosphere.
Answer: 273.

Class 10 Physical Science WBBSE

Question 29. Attractive forces and size effects in a gas can be neglected at ________.
Answer: low pressure and high temperatures.

Question 30. P, V, and T stand for pressure, volume and temperature of a gas _______ will express Boyle’s law.
Answer: \(V \times \frac{1}{P} \text { when } T \text { is constant }\)

Question 31. The relation between Celsius and absolute scale is ________.
Answer: T = t + 273.

Question 32. Normal pressure is _________.
Answer: 1.013 106 dyne/cm².

Question 33. Gases often deviate from the ideal gas behaviour because their molecules __________.
Answer: have forces of attraction between them.

Question 34. In the ideal gas equation PV = nRT, the value of R depends upon _________.
Answer: unit of measurement.

Question 35. At constant mass and constant volume, the relation between pressure and temperature is _________.
Answer: Gay Lussac’s law.

 

Chapter 2 Behaviour Of Gases Mathematical Problem

Question 1. A gas is allowed to expand at a constant temperature from an initial volume of 200 ml to a final volume 200 ml. At the end of the expansion the pressure of the gas was found to be in I atmosphere, what was the initial pressure of the gas?
Answer:

Given

A gas is allowed to expand at a constant temperature from an initial volume of 200 ml to a final volume 200 ml. At the end of the expansion the pressure of the gas was found to be in I atmosphere

V₁ = initial volume of the gas = 200ml

P₁ = initial pressure of the gas =? atm

V₂= final volume of the gas = 1200 ml

P₂  = final pressure of the gas = 1 atm.

From Boyle’s law,

P₁V₁ = P₂V₂

X x 200 = 1 x 1200

\(X=\frac{1200}{200}\)

= 6 atoms

The initial pressure of the gas is 6 atm.

Question 2. A certain volume of the gas was found to be at a pressure of 1000 mm of mercury. When the pressure was decreased by 500 mm the gas occupied a volume of 2000 Cm³?
Answer:

Calculate the initial volume occupied by the gas if the change was done at a constant temperature.

V₁ = Initial volume of the gas = ? Cm³

P₁ = Initial pressure of the gas = 100 mm.

V₂ = Final volume of the gas = 2000 Cm³

P₂ = Final pressure of the gas = 500 m

From Boyle’s law,

P₁V₁ = P₂V₂

1000 × 500 × 2000

\(x=\frac{500 \times 2000}{1000}\)

= 1000 Cm³

The initial volume occupied by the gas is 1000 Cm³.

Question 3. A vessel of volume 2000 cm3 contains 0.1 mol of oxygen and 0.2 mol of carbon dioxide. If the temperature of the mixture is 300 K. Find its pressure.
Answer:

Given

A vessel of volume 2000 cm3 contains 0.1 mol of oxygen and 0.2 mol of carbon dioxide. If the temperature of the mixture is 300 K.

We know, \(\mathrm{p}=\frac{\mathrm{nRT}}{\mathrm{V}}\)

The pressure due to oxygen is

\(p_1=\frac{(0.1 \mathrm{~mol})\left(8.3 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\right)(300 \mathrm{~K})}{\left(2000 \times 10^{-6} \mathrm{~m}^{-3}\right)}\)

= 1.25 x 10⁵ pa

Similarly, the pressure due to carbon dioxide

P₂ = 2.50 x 10⁵ pa

The total pressure in the vessel

P = P₁ + P₂

= (1.25 + 2.50) x 10⁵ pa

=3.75 x 10⁵ pa

The total pressure in the vessel =3.75 x 10⁵ pa