Question

as a gas occupied a volume of 250cc at 250at 700mm pressure temperature,25degree Celsius what additional pressure is required?reduse the volume to its 4/5at same temperature.

Answer 1

Additional pressure required : 175 mm

Further explanation

Boyle's Law  

At a constant temperature, the gas volume is inversely proportional to the pressure applied  

$\rm p_1V_1=p_2.V_2\\\\\dfrac{p_1}{p_2}=\dfrac{V_2}{V_1}$

V₁=250 ml

P₁=700 mmHg

$\tt V_2=\dfrac{4}{5}\times 250=200~ml$

$\tt P_2=\dfrac{P_1.V_1}{V_2}\\\\P_2=\dfrac{700\times 250}{200}=875~mmHg$

Additional pressure :

$\tt 875-700=175~mm$