Camphor is often used in molecular mass determination because

The addition of $0.643 \,g$ of a compound to $50 \,mL$ of benzene (density $= 0.879 \,g \,mL^{-1}$) lowers the freezing point from $5.51^{\circ}C$ to $5.03^{\circ}C$. If the freezing point constant,$K_f$ for benzene is $5.12 \,K \,kg \,mol^{-1}$,the molar mass of the compound is approximately $..... \,g \,mol^{-1}$.

An aqueous solution containing $0.2 \ g$ of a non-volatile solute '$A$' in $21.5 \ g$ of water freezes at $272.814 \ K$. If the freezing point of water is $273.16 \ K$,the molar mass (in $g \ mol^{-1}$) of solute '$A$' is $[K_f(H_2O) = 1.86 \ K \ kg \ mol^{-1}]$

What is the molality of a solution that has a freezing point depression of $3 \ K$ and a freezing point depression constant of $5 \ K \ kg \ mol^{-1}$ (in $m$)?

Which aqueous solution has the minimum freezing point?

What is the value of $K_{f}$ if $30 \ g$ urea (molar mass $60$) dissolved in $0.5 \ dm^{3}$ of water decreases the freezing point by $0.15^{\circ}C$?