The diagram illustrates a method for preparing copper(II) sulfate crystals. What are the functions of step 3 and step 4?
- Astep 3: to ensure all of the acid has reacted; step 4: to obtain solid copper(II) sulfate
- Bstep 3: to ensure all of the acid has reacted; step 4: to remove excess copper(II) oxide
- Cstep 3: to speed up the reaction; step 4: to obtain solid copper(II) sulfate
- Dstep 3: to speed up the reaction; step 4: to remove excess copper(II) oxide