How many grams are in 4.5 moles of sodium

Can someone me with questions 12 and 13 plz.

According to each substances heat of fusion, which of the items below requires more heat to be added per gram of substance to go from solid to liquid? silver sulfur water lead

For each of the following compounds, decide whether the compound's solubility in aqueous solution changes with ph. if the solubility does change, pick the ph at which you'd expect the highest solubility. you'll find ksp data in the aleks data tab. compounds does solubility change with ph