Which solution will have a higher boiling point: a solution containing 15 grams of sucrose (c12h22o11) in 25 grams of water or a solution containing 35 grams of sodium chloride in 500 grams of water?

A solute rises the boiling point of a solution, in direct relation with the number of particles added to the solution. Sucrose remains a molecule, does not separate into anything. NaCl gives Na+ + Cl-. 

Molar mass of sucrose is 12*12+22*1+11*16=144+22+176=342 

105g sucrose is 105/342=0.3moles ---> 0.3 moles of particles (molecules) 

Molar mass of NaCl is 23+35.5=58.5 

35 grams of NaCl is 35/58.5=0.598 >0.598*2=1.1974 moles of particles (ions, Na+ and Cl-) 

So, 35 grams of sodium chloride in 500 grams of water will have a higher boiling point