Which of the following has higher surface tension: pure water or soapy water?

At the same temperature and pressure,the rate of diffusion of helium with respect to methane is ...... .

The three states of matter are the result of what?

At $298 \ K$, a flask '$A$' of unknown volume $(V)$ contains oxygen at $5 \ atm$. Another flask '$B$' of volume $2 \ L$ contains helium at $3 \ atm$. Two flasks are connected together by a small tube of zero volume. After the two gases are completely mixed, if the resulting mixture is found to have the mole fraction of oxygen as $0.2$, the volume of flask '$A$' (in $L$) is (Assume oxygen and helium as ideal gases)

At ${100\,^o}C$ and $1\ L$,if the density of liquid water is $1.0\ g\ cm^{-3}$ and that of water vapour is $0.0006\ g\ cm^{-3}$,then the volume occupied by water molecules in $1\ L$ of steam at that temperature is .................. $cm^3$.

$20 \, L$ of $SO_2$ diffuses through a porous partition in $60 \, s$. Volume of $O_2$ diffused under similar conditions in $30 \, s$ will be ................ $L$. (in $.14$)