The answer is 37.5 moles
The explanation:
1- when we have the mass of SO3 in Kg so, first we have to convert it to grams:
mass = 3 * 1000 = 3000 g
2- we need to get the molar mass of SO3 :
molar mass of SO3 = 32 + (16*3)
= 80 g/mol
3- then we can use this formula to get number of moles:
moles = mass / molar mass
= 3000 g / 80 g/mol
= 37.5 moles
if 105 grams burns completely
therefore
105 ×22.4/48=49
