Two soap bubbles of radii $r_1$ and $r_2$ equal to $4\mathrm{cm}$ and $5\mathrm{cm}$ are touching each other over a common surface ${\mathrm{S}}_1{\mathrm{S}}_2$ (shown in figure). Its radius will be 

 

Nature of meniscus for liquid having angle of contact as $0°$ is

For water does not wet a glass rod, the angle of contact is

The liquid meniscus in capillary tube will be convex, if the angle of contact is

When the temperature is increased the angle of contact of a liquid _____.