How many ml of 2m hbr are needed to exactly neutralize 20 ml of 4m koh ?

 = 40 mL

Explanation:

Using the dilution formula;

M1V1 = M2V2

where M1 is the initial concentration, V1 is the initial volume, M2 is the concentration attained while V2 is the new volume.

Therefore;  To get the new volume;

V2 = M1V1/M2

     = ( 20mL × 4 M)/ 2 M

     = 40 mL

more info ? ? i don't understand what the question is

explanation:

there are two significant figures.