Convert 5×10^-3 milliliters to microliters.

• A. 0.005 μL
• B. 5 μL
• C. 50 μL
• D. 500 μL

Answer: (B)

Converting milliliters to microliters uses the fact that 1 mL equals 1000 μL. So multiply the volume in milliliters by 1000 to get microliters. Here, 5×10^-3 mL is 0.005 mL. Multiplying by 1000 μL per mL gives 0.005 × 1000 = 5 μL. An easy way to see this is to shift the decimal three places to the right. The result is five microliters.