If 100 grams of a saturated solution of lead nitrate is cooled from 60c to 20c, what will happen

Answer 1

Some of the Pb(NO3)2 will crystallize since the solubility is less at 20C that at 60C.

Answer 2

100g of Pb(NO3)2 dissolve 0.297moles. 1000g of Pb(NO3)2 will dissolve 0.297*1000/100=2.97 mol/dm3