Final answer:
The most accurate equipment for obtaining a 5.0 ml sample of a liquid is a pipette, specifically designed for precise volume measurements.
Step-by-step explanation:
To obtain a 5.0 ml sample of a liquid with high accuracy, the most appropriate piece of equipment would be a pipette. A pipette is designed to deliver a precise volume of liquid. Beakers and test tubes are not as precise and are typically used for holding or mixing liquids rather than measuring specific volumes. Graduated cylinders can also measure volumes but are less accurate for small volumes compared to a pipette. For very accurate measurements of small volumes, a micropipette might be used, as it is specifically designed to dispense small amounts of liquid with high precision. However, for general laboratory use and versatility, a conventional glass or plastic pipette would be the best choice when a specific volume like 5.0 ml is needed.