Answer:
Yellow, Purple
Step-by-step explanation:
5. The law of conservation of mass essentially states that the total 'mass' that you started with equals to the total 'mass' at the end. Take the burning of a tree, for example. Although the tree loses mass, the mass of carbon dioxide and other molecules increases proportionally to the rate of tree mass loss. Abiding by this law in a chemical reaction, we should expect the amount of shapes on each side to be equal, although they may not necessarily be in the same form. This is only shown in the 'Yellow' square.
6. We want the same amount of stuff on the left as we do on the right. There is 2 Nitrogen and 2 Hydrogen on the left. There is 1 Nitrogen and 3 Hydrogen on the right. To balance these amounts out, we'd need to multiply a few things:
1 Nitrogen by 2 on the right to make things even, meaning that now there is 2 Nitrogen and 6 Hydrogen on the right. To balance this out on the left, we need to multiply the 2 Hydrogen by 3 to yield 6 Hydrogen.
As such, the new equation is N2+ 3H2 --> 2NH3.
Do we have the same amount of stuff on the left as we do on the right? Yes! So the equation is balanced.