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

The $O_2$ gas is collected over water at $400 \ K$ temperature in a $2 \ L$ vessel. If the total pressure of the mixture is $33.26 \ bar$ and the pressure of dry $O_2$ gas is $32.20 \ bar$,find the vapour pressure of water under the same conditions.

At $27^{\circ} C$, a closed vessel contains a mixture of equal weights of helium (mol. wt. = $4$), methane (mol. wt. = $16$) and sulphur dioxide (mol. wt. = $64$). The pressure exerted by the mixture is $210 \ mm$. If the partial pressures of helium, methane and sulphur dioxide are $p_1, p_2$ and $p_3$ respectively, which one of the following is correct?

Which of the following statements is incorrect?

One atmosphere is equal to

If two molecules of $A$ and $B$ have molar masses of $100 \ g/mol$ and $64 \ g/mol$ respectively,and the rate of diffusion of $A$ is $12 \times 10^{-3} \ mol/s$,then the rate of diffusion of $B$ will be: