Question

What is the weight of oxygen required for complete combustion of 2.86 kg of ethylene

Answer 1

Combustion of Ethylene can be written as:
C2H4 + 3 O2 → 2 CO2 + 2 H2O
0.028 kg (Molar mass of ethylene) needs 3 x 0.032 = 0.096 kg of oxygen.
1 kg of ethylene will need (0.096/0.028) = 3.42 kg of oxygen.
So, 2.86 kg of ethylene will need (3.42 x 2.86) = 9.7812 kg of oxygen.