Properties of Matter - Physics For Class IX (Science Group) - Numericals

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Physics For Class IX (Science Group)
UNIT 7: PROPERTIES OF MATTER
Numericals

WORKED EXAMPLES

Numerical From Text Book Exercise

Gases and Kinetic theory
7. The pressure on 9 cm³ of oxygen gas is doubled at a fixed temperature. What will its volume become?
Solution:
Data:

• Initial pressure = P₁ = P₁
• Final pressure = P₂ = 2P₁
• Initial volume = V₁ = 9 cm³
• Final Volume = V₂ = ?

Working Formula:

P₁V₁ = P₂V₂

Calculation:

P₁ x (9) = (2P₁) x V₂

Ans: Hence, Its volume will become 4.5 cm³

8. A container holds 30 m³ of air at a pressure of 150000 Pa. If the volume changed to 10 m³ by decreasing load on the piston. What will the pressure of the gas become? Assume that its temperature remains constant.
Solution:
Data:

• Initial pressure = P₁ = 150000 Pa
• Final pressure = P₂ = ?
• Initial volume = V₁ = 30 m³
• Final Volume = V₂ = 10 m³

Working Formula:

P₁V₁ = P₂V₂

Calculation:

(150000) x (30) = P₂ x (10)

4500000 = P₂ x (10)

P₂ = ^4500000/₁₀ = 450000 pa.

Ans: Hence, The pressure of the gas will become 450000 pa

9. Air at atmospheric pressure of 760 mm of Hg is trapped inside a container available with a moveable piston. When the piston is pulled out slowly so that the volume is increased from 100 dm³ to 150 dm³, the temperature remaining constant. What will be the pressure of the air becomes?
Solution:
Data:

• Initial pressure = P₁ = 760 mm of Hg
• Final pressure = P₂ = ?
• Initial volume = V₁ = 100 dm³
• Final Volume = V₂ = 150 dm³

Working Formula:

P₁V₁ = P₂V₂

Calculation:

(760) x (100) = P₂ x (150)

76000 = P₂ x (150)

P₂ = ⁷⁶⁰⁰⁰/₁₅₀ = 506.67 mm of Hg

Ans: Hence, The pressure of the air will become 506.66 mm of Hg