The osmotic pressure of a $0.5 \ M$ aqueous solution of $CH_3COOH$ having a $pH$ of $2$ at temperature $T$ is . . . . . . . (in $RT$)

Which one of the following statements is false?

$100 \ mL$ of $1.5\%(w/v)$ solution of urea has an osmotic pressure of $6.0 \ atm$ and $100 \ mL$ of $3.42\%(w/v)$ solution of cane sugar has an osmotic pressure of $2.4 \ atm$. If the two solutions are mixed,the osmotic pressure of the resulting solution in $atm$ is (Assume that there is no reaction between urea and cane sugar).

$2.5 \ g$ of a non-volatile,non-electrolyte is dissolved in $100 \ g$ of water at $25^{\circ} C$. The solution showed a boiling point elevation by $2^{\circ} C$. Assuming the solute concentration is negligible with respect to the solvent concentration,the vapour pressure of the resulting aqueous solution is . . . . . . $mm$ of $Hg$ (nearest integer).
[Given : Molal boiling point elevation constant of water $(K_b) = 0.52 \ K \ kg \ mol^{-1}$,
$1 \ atm$ pressure $= 760 \ mm$ of $Hg$,molar mass of water $= 18 \ g \ mol^{-1}]$

$A$ solution containing $1.8 \ g$ of a compound (empirical formula $CH_2O$) in $40 \ g$ of water is observed to freeze at $-0.465 \ ^oC$. The molecular formula of the compound is ($K_f$ of water $= 1.86 \ K \ kg \ mol^{-1}$)

If the mole fraction of the solvent decreases while preparing a solution,then ...........