Gram stain bottle 144 mL; each slide 18 mL; slides stained.

Gram stain bottle 144 mL; each slide 18 mL; slides stained.

• A. 2 slides
• B. 6 slides
• C. 8 slides
• D. 4 slides

Answer: (C)

You determine how many slides you can stain by dividing the total available volume by the volume used per slide. With 144 mL in the Gram stain bottle and 18 mL needed per slide, you can stain 144 ÷ 18 = 8 slides. This matches exactly because 8 × 18 = 144, so the bottle is used up with eight slides and nothing is left over. Any attempt to stain more would require more reagent than you have, while staining fewer would leave reagent unused.

You determine how many slides you can stain by dividing the total available volume by the volume used per slide. With 144 mL in the Gram stain bottle and 18 mL needed per slide, you can stain 144 ÷ 18 = 8 slides. This matches exactly because 8 × 18 = 144, so the bottle is used up with eight slides and nothing is left over. Any attempt to stain more would require more reagent than you have, while staining fewer would leave reagent unused.