Putting glue on something, because once it is set in you cannot change it back.
Explanation:
Mole ratio of Zn to HCl = 1 : 2.
If we use all 2.0mol of Zn, we would need 2.0 * 2 = 4.0mol of HCl. However we only have 3.0mol of HCl.
Therefore HCl is limiting.
Now I'm just going to assume you mean Charles law. So when working with gases, there are 4 properties: pressure, volume, temp, and quantity. The simple gas laws deal with 2, while leaving the other 2 constant. If Charles' Law changes temp and volume, what 2 stay constant? Pressure and quantity