Which machine spins samples at high speeds to separate components by density?

• A. Spectrophotometer
• B. Incubator
• C. Centrifuge
• D. Grinder

Answer: (C)

The main concept tested is using high-speed rotation to separate components by density. A centrifuge spins samples at thousands of revolutions per minute, creating a strong centrifugal force. This force causes heavier, denser components to move outward toward the outer edge, while lighter components stay closer to the center. As a result, distinct layers or pellets form, making it possible to separate and collect the different components. This method is widely used in labs for separating blood components, cellular debris, or purified substances because density differences drive the separation.

The other devices work for different purposes. A spectrophotometer measures how much light a sample absorbs to estimate concentration, not to separate components. An incubator provides a controlled temperature and environment for growing organisms, not for physical separation. A grinder reduces particle size, not separates substances by density.