The insoluble base that can be mixed with sulfuric acid to make zinc sulfate is zinc oxide (ZnO).

Here's why:

* Insoluble Base: Zinc oxide is a metal oxide and is considered an insoluble base. It doesn't readily dissolve in water.

* Reaction with Sulfuric Acid: When zinc oxide reacts with sulfuric acid (H₂SO₄), it undergoes a neutralization reaction, forming soluble zinc sulfate (ZnSO₄) and water (H₂O):

ZnO (s) + H₂SO₄ (aq) → ZnSO₄ (aq) + H₂O (l)

This reaction is a common way to synthesize zinc sulfate, which has various industrial applications.