# Numerical Problem, boyle’s law, For Class 9, ICSE

Hello my students, today we discussing  some numerical application on Gas equation.

Prob 1:

A gas occupies 600 cmunder a pressure of 700 mm Hg. Find under what  pressure the volume of the gas will be reduced by 20 percent of its original volume, The Temperature remaining constant throughout.

Ans:

Given Data: Initial pressure P1 = 700 mm Hg,  Initial volume V1 =  600 cm3

Final Volume V2 = 20 percent of its original volume = ( 600-20 percent of 600) = ( 600 -120) = 480 cm3

P2 =?

From Boyels law P1 V1 = P2 V2

700 X 600 = P2 x 480

P2 = 875 mm Hg ( Ans)

Prob 2.

Two cylinder, both containing carbon di oxide, are connected together by a tube fitted with a tap. The capacity of one cylinder is 4 dm3 and that of other 1 dm3, the Pressure in the first cylinder is 560 mm Hg and that in second 1000 mm Hg. What will be the final pressure in both cylinders on opening the Tap, If the temperature remains constant.

Ans:   P1 = 560 mm Hg , P2 = ?, V1 = 4 dm3      V2 = ( 4+1 ) dm3

Applying boyle’s law  P1 V1 = P2 V2

560 x 4 =P2 x 5

P2 = 448 mm Hg

2nd case ( for 2nd cylinder )

Applying boyle’s law  P1 V1 = P2 V2

1000 x 1 =P2 x 5

P2 = 200 mm Hg

Final pressure  448+200 = 648 mm Hg ( Ans )

Prob 3

The volume of a given mass of a gas with some pieces of marble in a container at 760 mm of pressure is 100 ml. If the pressure is changed to 1000 mm of Hg, the new volume is 80 ml. Find out the volume occupied by the marble pieces, if the temperature remains constant.

Ans: Let volume occupied by the marble = V ml

at 760 mm Hg ,the volume occupied by gas = ( 100 – V) ml

at 1000 mm Hg ,the volume occupied by gas = ( 80 – V) ml

Applying boyle’s law  P1 V1 = P2 V2

760 x ( 100-V) = 1000 ( 80 – V)     solve V

Prob 4

The Pressure of gas A ( PA ) is 3.0 atm when it occupies 5 L of the Volume. Calculate the Final pressure when it is compressed to 3.0L volume at constant Temperature.

Ans: PA = 3.0 atm , Va = 5 ltr    , Pb = ? , Vb = 3 ltr

Applying boyle’s law  P1 V1 = P2 V2 , Put value and solve Pb

Writer Identity:  Sourav Sir is a well-known Chemistry faculty of Aims ( a well known JEE Main & Advanced and NEET Coaching institute in Barrackpore) . He hold Bachelor of Civil engineering ( BE) & Master of Civil Engineering ( ME) from Jadavpur University, He also did MBA (F) and A Chartered Engineer from Institute of Engineers (I). To contact the author please call Aims: +917003557150,+918697234172,+919748932154 Or Email : haldarsourav@gmail.com or log in: http://aimscognitive.com/.