Question

What is the required volume of an acid to prepare 2 L of solution a 10% (v/v).

Answer 1

ASSUMING the acid you're using is 100%, then for 10% v/v you want 10 mL acid/100 mL solution. So scale that up from 100 mL to 2,000 mL.
10 mL x (2000 mL/100 mL) = ?
Most acids are not 100%.