This is a simple unit conversion problem.
1 mL= 1 x 10⁻³ L
1 μL = 1 x 10⁻⁶ L
So, we can convert 250 mL and 13.5 μL into L as follows,
250 mL = 250 x 10⁻³ L
13.5 μL = 13.5 x 10⁻⁶ L
1 experiment requires 13.5 μL of HCl.
Hence,
the number of experiments = total volume / volume per experiment
= 250 x 10⁻³ L / 13.5 x 10⁻⁶ L
= 18518.518
= 18518
(number of experiments should be a whole number. Hence we have to choose 18518)
Hence, the number of experiments which can be performed is about 18500.
