If $5\%$ sugar solution is isotonic with $1\%$ solution of unknown substance,then find out the molecular mass of the unknown substance. (in $g/mol$)

The solution in which the blood cells retain their normal form is with regard to the blood:

If the osmotic pressure of cane sugar solution is $2.46 \ atm$ at $27^{\circ} C$,then what is the concentration (in $mol \ L^{-1}$) of the solution $(R=0.0821 \ L \ atm \ mol^{-1} \ K^{-1})$?

If a solution has an osmotic pressure of $0.82 \ bar$ at $27 \ ^oC$,find the concentration of such a solution. (in $M$)

What is the osmotic pressure of a semi-molar solution at $27^{\circ} C$ (in $atm$)?
$(R = 0.082 \ L \ atm \ K^{-1} \ mol^{-1})$

$A$ solution containing $10 \ g$ of urea (molar mass $= 60 \ g \ mol^{-1}$) per liter is isotonic with a $5 \% \ w/v$ solution of a non-volatile solute. The molar mass of the non-volatile solute is ......... $g \ mol^{-1}$.