If 5.0 moles of c3h8 react, how many molecules of water are formed?

Balance Chemical Equation for combustion of Propane is as follow,

                         C₃H₈  +  5 O₂    →    3 CO₂  +  4 H₂O

According to equation,

              1 mole of C₃H₈ on combustion gives  =  4 moles of H₂O
So,
        5 moles of C₃H₈ on combustion will give  =  X moles of H₂O

Solving for X,
                                    X  =  (5 mol × 4 mol) ÷ 1 mole

                                    X  =  20 moles of H₂O

Calculating number of molecules for 20 moles of H₂O,
As,
                        1 mole of H₂O contains  =  6.022 × 10²³ molecules
So,
                20 moles of H₂O will contain  =  X molecules

Solving for X,
                                 X  =  (20 mole × 6.022 × 10²³ molecules) ÷ 1 mol

                                 X  =  1.20 ×10²⁵ Molecules of H₂O