Taq DNA polymerase is used to catalyze polymerase chain reactions (PCR). When you purchase this enzyme, a 10x buffer (200 mM Tris HCl at pH 8.4, 500 mM KCl) is supplied with it. The buffer should be diluted to 1x concentration in PCR. How much 10x buffer do you need to use for a 20ul reaction? What is the final working concentrations of KCl in the reaction when you use Taq to perform PCR?