What does a semi-permeable membrane allow to pass through?

Which of the following solutions will not show flow of solvent in either direction when separated by a semipermeable membrane?

When kept in water,a raisin swells in size. Name and explain the phenomenon involved with the help of a diagram. Give three applications of the phenomenon.

Explain reverse osmosis and the purification of water.

The swelling in feet and ankles of an aged person due to sitting continuously for long hours during travel,is reduced by soaking the feet in warm salt water. This is because of

$A$ $5\% \ (w/v)$ solution of anhydrous $CaCl_2$ at $0^o C$ exerts an osmotic pressure of $15 \ atm$. The degree of dissociation $(\alpha)$ of $CaCl_2$ is ....... $\%$.