Assertion: Pressure in bubble (r) in the atmosphere of pressure $P_0$ is $P_0+\frac{4\sigma }{r}$ where $r$ is the radius and $\sigma$ is surface tension.

Reason: $\frac{4\sigma }{r}$ is the excess pressure due to two surfaces exposed to the atmosphere.

Assertion: Rise of water level in capillary tube should be accounted vertically and not as the length of pipe in which it has raised.

Reason: More the radius, the rise will decrease in the different liquids tested.

Assertion: When there is a thin layer of water between two glass plates, there is a strong attraction between them.

Reason: The pressure between the plates becomes less than atmospheric pressure because pressure inside a bubble or drop is greater than outside pressure.

A glass capillary tube of radius $r$ is placed vertically touching the surface of water. The water rises to height $h$ in capillary tube. If now the tube is dipped into water till only $\frac{h}{2}$ length of it is outside the water surface, the radius of curvature of the meniscus of water in capillary tube will be,

A capillary is dipped in a water vessel kept on a freely falling lift. Then,

Two spherical soap bubbles of radii $r_1$ and $r_2$ in vacuum coalesce under isothermal conditions. The resulting bubble has a radius $R$ such that,

Water rises to a height of $5 \mathrm{cm}$ in a glass capillary tube. If the area of cross-section of the tube is reduced to ${\left(\frac{1}{16}\right)}^{\mathrm{th}}$ of the former value, the water rises to a height of,

Suppose $64$ raindrops combine to form a single drop. Calculate the ratio of the total surface energy of the $64$ drops to that of a single drop. $(T=0.072 \mathrm{N} {\mathrm{m}}^{-1})$

Two separate air bubbles (radii $0.002\mathrm{m}$ and $0.004\mathrm{m})$ formed of same liquid (Surface tension $0.07\mathrm{N}/\mathrm{m}$) come together to form a double bubble. Find the radius of curvature in $\mathrm{mm}$ of the internal film surface common to both the bubbles.