When the temperature increases,the surface tension of water $......$

Pressure of a gas in a vessel can be measured by

The rate of diffusion of a gas is ..... times that of hydrogen. (Molecular weight = $98$)

The molecular weight of a gas which diffuses through a porous plug at $1/6^{th}$ of the speed of hydrogen under identical conditions is

$50 \ mL$ of hydrogen gas diffuses through a small hole in a container in $20 \ min$. How much time (in $min$) will $40 \ mL$ of oxygen take to diffuse under the same conditions?

The ratio of rates of diffusion of gases $X$ and $Y$ is $1:5$ and that of $Y$ and $Z$ is $1:6$. The ratio of rates of diffusion of $Z$ and $X$ is