\(50\,\text{g}\) of a substance is dissolved in \(1\,\text{kg}\) of water at \(+90^\circ\text{C}\). The temperature is reduced to \(+10^\circ\text{C}\). The density is increased from \(1.1\) to \(1.15\,\text{g cc}^{-1}\). What is the % change of molarity of the solution?