Answer
Strong acids: $H_2SO_4$, $HCl$, $HBr$ and $HI$.
Strong bases: $NaOH$, $KOH$, $Ca(OH)_2$ and $Ba(OH)_2$.
Work Step by Step
There are 7 common strong acids and 8 common strong bases:
Acids: $HCl, HBr, HI, HClO_4, HClO_3, H_2SO_4$ and $HNO_3$.
Bases: $NaOH, KOH, Ba(OH)_2, LiOH, RbOH, CsOH, Sr(OH)_2$ and $Ca(OH)_2$.
The easiest way to know this list is to memorize it, and you can find it in textbooks, or in the internet.
