Companion cells in plants are associated with

The vapor pressure of water at $80\,^oC$ is $355.5\, mm$ of $Hg$. $A$ $100\, mL$ vessel contains $O_2$ gas at $80\,^oC$ saturated with water vapor,and the total pressure is $760\, mm$ of $Hg$. If the contents of the vessel are transferred to a $50\, mL$ vessel at the same temperature,what will be the partial pressure of $O_2$ in $mm$?

What is the entropy change in $J K^{-1}$ during the melting of $27.3 \ g$ of ice at $0^{\circ} C$? (Latent heat of fusion of ice $= 330 \ J g^{-1}$)

$A$ random variable $X$ takes the values $0, 1$ and $2$. If $P(X=1)=P(X=2)$ and $P(X=0)=0.4$,then the mean of the random variable $X$ is

$A$ metal $M$ readily forms its sulphate $MSO_4$,which is water soluble. It forms oxide $MO$ which becomes inert on heating. It forms insoluble hydroxide which is soluble in $NaOH$. The metal $M$ is

The work function of a metallic surface is $5.01 \ eV$. The photo-electrons are emitted when light of wavelength $2000 \ \mathring{A}$ falls on it. The potential difference applied to stop the fastest photo-electrons is ............. $volts$ $[h = 4.14 \times 10^{-15} \ eV \ s]$