Help please

Question

A room of 1.5 litres contains gas with pressure 10^5 Pa.If the gas particle has average speed of 750 m/s,then gas mass that trapped in the room is...gram

A.0.8
B.0.7
C.0.6
D.0.5
E.0.4

Answer 1

Energy of the gas, E = 3/2 nRT 

PV = nRT

so E = 3/2 PV

 

Kinetic Energy of the gas, KE = 1/2 mv²

sp KE = E

 

3/2 PV = 1/2 mv²

thus m = 3PV/v² 

convert everything to SI units i.e. Litres to metres, Pascals and seconds

 

1 Pa = 1 kg/(m·s²)

 

m = 3 (10⁵ Pa)(1.5*10^-3 m)/(750 m/s)²

m = 0.8 g