Answer:
D.) 4
Explanation:
Al + 3 O₂ --> 2 Al₂O₃
In the equation, there are:
Reactants: 1 Al and 6 O
Products: 4 Al and 6 O
To determine how many atoms there are of each, you multiply the coefficients by the subscripts attached to the atoms. While the question doesn't ask, as you can see, the oxygen atoms are balanced because there is an equal amount on both sides. To balance the aluminum atoms, you can get 4 aluminum atoms on the reactants side by using a coefficient of 4.
The new equation would look this this:
4 Al + 3 O₂ --> 2 Al₂O₃
There are now:
Reactants: 4 Al and 6 O
Products: 4 Al and 6 O
