Propane burns completely: . What is ?

Answer and explanation

Correct answer: A.

  1. Step 1: Oxygen atoms on the right: .
  2. Step 2: Each molecule supplies atoms, so .
Answer
.
Why not the others: : counts only the oxygen needed for the carbon dioxide. : counts only the oxygen needed for the water. : counts oxygen atoms instead of oxygen molecules.

Practise more Chemical reactions, formulae and equations.

Free questions with an explanation for every one, and full timed ESAT (Engineering and Science Admissions Test) mock tests.