Pipette delivers fixed volume when filled to mark

Steps:

• Identify apparatus functions: burette for variable titration volumes, gas syringe for adjustable gas collection, measuring cylinder for approximate liquid volumes, pipette for precise fixed delivery.
• Determine filling consistency: only pipette requires filling to a specific etched mark for accuracy.
• Compare to others: burette starts full but drains variably; gas syringe volume set by plunger; measuring cylinder filled to any desired level.
• Conclude pipette ensures reproducibility by always using the same fill level.

Why D is correct:

• A pipette is defined as a calibrated tool that delivers an exact, fixed volume (e.g., 10 mL) when liquid is filled to the mark and dispensed.

Why the others are wrong:

• A: Burette measures variable volumes during titrations, not fixed levels.
• B: Gas syringe adjusts volume by moving the plunger to collect different gas amounts.
• C: Measuring cylinder measures any volume up to its capacity, not a consistent level.

Final answer: D