CBSE Class 12-science Answered

Solubility of sodium nitrate at 25^oC is 92.1 g/ 100 mL i.e. 92.1 g sodium nitrate is dissolved in 100 mL of water. Since density of water is 1, we can say that 92.1 g sodium nitrate is dissolved in 100 g of water.

Since saturated solution contains 50 g of water amount of sodium nitrate that can be dissolved in it will be 46.05 g at 25^oC.

As temperature increases solubility of sodium nitrate increases.

The saturated solution is cooled from 50^oC to 30 ^oC. Since  solubility of sodium nitrate will be 46.05 g/ 50 mL at 25^oC, above 25^oC sodium nitrate will remain soluble. Hence no sodium nitrate will separate when the solution is cooled from 50^oC to 30 ^oC.