To validate a P1000 micropipette, 560 μL of water should weigh approximately

• A. 0.56 g
• B. 5.60 g
• C. 0.056 g
• D. 56 g

Answer: (A)

When validating a P1000 micropipette, you use a gravimetric check: water’s mass closely matches its volume in milliliters because of its density. Water has about 1 g per 1 mL, so 1 μL (one thousandth of a milliliter) weighs about 0.001 g (1 mg). Therefore, 560 μL of water should weigh roughly 0.56 g (560 × 0.001 g).

So the expected mass is 0.56 g. The other weights would imply volumes that are either ten times larger, ten times smaller, or a hundred times larger than 560 μL, which doesn’t match the given volume. This relationship helps ensure the pipette is delivering the correct amount.