According to the USA, an acceptable non-graduated medicine dropper delivers ___ drops of water weighing __ g at ___ degrees C.

• A. 20, 1, 15
• B. 15, 0.5, 20
• C. 25, 1.5, 25
• D. 10, 0.5, 10

Answer: (A)

When using a non-graduated dropper, you estimate volume by counting drops, and for water the rough rule is that 20 drops make about 1 mL. At a reference temperature of about 15°C, the density of water is essentially 1 g/mL, so those 20 drops weigh about 1 gram. This gives a convenient standard: 20 drops of water ≈ 1 g at 15°C. The other options would imply different masses for the same drop count or rely on densities at temperatures that don’t align with that standard, so they don’t fit the accepted reference.