Concentration Expressions

Give Reason: Concentration is expressed in molality and not molarity?

Dependance of rate on concentration is expressed by

When the concentration is expressed as the number of moles of a solute per kg of solvent it is known as

A solution concentration is expressed in molarity and not in molality while considering osmotic pressure. Why?

If the concentration is expressed in moles per liter, the unit of the rate constant for a first-order reaction is

Write units of rate constant for zero order and for the second order reactions if the concentration is expressed in mol L^(-1) and time in second.