So, let's balance the following chemical reaction:
To balance a chemical equation, we could follow the steps:
1. We need to check that the number of atoms of each element before and after the reaction takes place, be the same. So, let's start to count:
As you can see, the numbers for each element are not the same so we need to balance the equation. Remember: When balancing a chemical reaction, we can change the coefficiens but we can't change the subscripts. And, we could balaance in the following order: Metals, nonmetals, hydrogen and oxygen.
In this case, let's start balancing Al and K, and then S:
Finally, you can notice that K is not balanced now, so we could multiply the coefficient 2*3 which gives us 6. And, if we make this change and count again, the balanced reaction will be:
And, the best coefficients are: 1,6,2,3.
Answer D is correct.