$A$ $0.6\%$ solution of urea (molecular weight $= 60$) would be isotonic with

$A$ $5.25\%$ solution of a substance is isotonic with a $1.5\%$ solution of urea (molar mass $= 60\ g\ mol^{-1}$) in the same solvent. If the densities of both the solutions are assumed to be equal to $1.0\ g\ cm^{-3},$ the molar mass of the substance will be .............. $g\ mol^{-1}$.

At $300 \ K$,$6 \ g$ of urea was dissolved in $500 \ mL$ of water. What is the osmotic pressure (in $atm$) of the resultant solution? $(R=0.082 \ L \ atm \ K^{-1} \ mol^{-1})$ $(C=12; N=14; O=16; H=1)$

Calculate the amount of solute dissolved in $3 \ dm^3$ water having osmotic pressure $0.3 \ atm$ at $300 \ K$. (Molar mass of solute $= 108 \ g \ mol^{-1}, R = 0.0821 \ atm \ dm^3 \ K^{-1} \ mol^{-1}$) (in $g$)

$A$ solution of polystyrene in benzene contains $10 \, g/L$. The equilibrium height of the column of solution having density $0.9 \, g/mL$ in the osmometer is $11 \, cm$ at $27 \, ^\circ C$. What is the average molar mass of polystyrene? (Assume the solution is ideal)

Which of the following would have the highest osmotic pressure? (Assume that all salts are $90\%$ dissociated.)