A calorimeter of negligible heat capacity contains $100 \mathrm{g}$ water at $40 °\mathrm{C}$. The water cools to $35 °\mathrm{C }$in $\mathrm{5 }\mathrm{m}\mathrm{i}\mathrm{n}$. If water is now replaced by a liquid of the same volume as that of water at the same initial temperature it cools to $35 °\mathrm{C}$ in $2 \mathrm{m}\mathrm{i}\mathrm{n}$. Given specific heats of water and liquid are $4200 \mathrm{J} \mathrm{k}{\mathrm{g}}^{-1} °{\mathrm{C}}^{-1}$ and $2100 \mathrm{J} \mathrm{k}{\mathrm{g}}^{-1} °{\mathrm{C}}^{-1}$ respectively. Find the density of liquid give the answer in $\mathrm{kg} {\mathrm{m}}^{-3}$. [Assume Newton law of cooling is applicable]