Answer:
Solubility of sucrose in water at 100°C is about 487 g/1000 g of water.
Since the solution is saturated, 1000 g of boiling water contains 487 g of sucrose.
Solubility of sucrose in water at 20°C is about 211 g/1000 g of water, so 211 g of sucrose will remain in solution.
The mass of sucrose that will crystallize out of the solution is 276 g (487 g - 211 g).
Therefore, the mass of rock candy that will be formed is 276 g.
So, the mass of rock candy that will be formed from the given solution of sucrose is 276 g.