In order to answer this, we mus know the data for the heat of combustion of propane. This is an empirical data that you can search online. The heat of combustion is -2220 kJ/mol. The molar mass of propane of 44.1 g/mol. The solution is as follows:
ΔH = -2220 kJ/mol (1 mol/44.1 g)(1000g/1kg)(20 kg)
<em>ΔH = -1006802.721 kJ or -1 GJ</em>
Mouthwash:
solvent - water
solute - alcohols
vinegar:
solvent - water
solute - acetic acid
bleach:
solvent - water
solute - sodium hypochlorite
hope this helps!!
I think the answer is B. I really don't remember but im pretty sure its that one.