Which state of matter has a definite volume but no definite shape?

Cyclopropane and oxygen at partial pressures $170 \ torr$ and $570 \ torr$ respectively are mixed in a gas cylinder. What is the ratio of the number of moles of cyclopropane to the number of moles of oxygen $(n_{C_3H_6}/n_{O_2})$ ?

The ratio of the partial pressure of a gaseous component to the total vapor pressure of the mixture is equal to .......

Pressure-volume $(pV)$ work done by an ideal gaseous system at constant volume is (where $E$ is internal energy of the system):

$A$ certain gas takes three times as long to effuse out as helium. Its molecular mass will be ........... $u$.

Define surface tension and provide its dimensions and $SI$ unit.