The osmotic pressure of a dilute solution of a non-volatile solute is

What is the effect of external pressure on the osmotic pressure $(OP)$ of a solution?

The osmotic pressure of a living cell is $12 \ atm$ at $300 \ K$. The strength of sodium chloride solution that is isotonic with the living cell at this temperature is $...... \ g \ L^{-1}$. (Nearest integer)
Given : $R = 0.08 \ L \ atm \ K^{-1} \ mol^{-1}$
Assume complete dissociation of $NaCl$
(Given : Molar mass of $Na$ and $Cl$ are $23$ and $35.5 \ g \ mol^{-1}$ respectively.)

What is the concentration (in $g/L$) of a sugar solution $(mol. wt. = 342 \, g/mol)$ that is isotonic with a $6 \, g/L$ urea solution $(mol. wt. = 60 \, g/mol)$?

Which one of the following pairs of solutions will be isotonic at the same temperature?

$A$ solution of a substance containing $1.05 \ g$ per $100 \ mL$ was found to be isotonic with $3 \% (w/v)$ glucose solution. The molecular mass of the substance is :