Which of the following must always be used with volumetric or graduated pipettes?

• A. A desiccator
• B. A wash bottle
• C. A burette clamp
• D. A pipette bulb or pipette filler

Answer: (D)

Verified step by step guidance

1. Understand the purpose of volumetric or graduated pipettes: These are precision instruments used to transfer specific volumes of liquid accurately in analytical chemistry experiments.
2. Recognize the importance of safety and accuracy: Pipettes require controlled suction to draw liquid into the pipette without contaminating the sample or risking exposure to hazardous chemicals.
3. Identify the tool used for suction: A pipette bulb or pipette filler is specifically designed to create suction, allowing liquid to be drawn into the pipette safely and precisely.
4. Explain why other options are not correct: A desiccator is used for drying substances, a wash bottle is used for rinsing, and a burette clamp is used for securing burettes. None of these are directly related to the operation of pipettes.
5. Conclude that a pipette bulb or pipette filler must always be used with volumetric or graduated pipettes to ensure safe and accurate handling of liquids.