Answer:
0.362 moles
Step-by-step explanation:
Mass of butane = 21g
Molar mass of carbon = 12g / mol
Molar mass of hydrogen = 1g/mol
Molar mass of butane ? = [(12*4) * (1*10)]
Molar mass of butane = 58g / mole
Number of moles = mass of molecules / molar mass of molecule
Number of moles = 21 / 58
Number of moles of butane = 0.362 moles
The number of moles in 21g of butane is 0.362 moles