Isotonic solutions have the same

Pure water can be obtained from sea water by

$18 \ g$ glucose (Molar mass $= 180 \ g/mol$) is dissolved in $100 \ mL$ of water at $300 \ K$. If $R = 0.0821 \ L \ atm \ K^{-1} \ mol^{-1}$,what is the osmotic pressure of the solution (in $atm$)?

Which one of the following is an isotonic pair of solutions?

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? $(R=0.082 \ L \ atm \ K^{-1} \ mol^{-1})$ $(C=12; N=14; O=16; H=1)$

Which of the following can pass through a semi-permeable membrane?