MLS Laboratory Equipment & Techniques 3

Question 1

Which class of fire extinguisher should be used for a burning electrical equipment fire in the laboratory?

Accepted Answer

Class C

Answer

Class C extinguishers use non-conductive agents (CO2 or dry chemical) suitable for electrical fires where water-based agents would be dangerous.

Question 2

When using a refractometer to measure urine specific gravity, the instrument measures:

Accepted Answer

The refractive index, which correlates with solute concentration

Answer

A refractometer measures how much light bends (refractive index) as it passes through the sample, which correlates with dissolved solute concentration and specific gravity.

Question 3

Which of the following describes the correct procedure when using a swinging-bucket rotor centrifuge for density gradient separations?

Accepted Answer

Balance opposing tubes to within manufacturer tolerances before spinning

Answer

Proper balancing of opposing buckets is essential to prevent rotor damage, instrument vibration, and potential centrifuge failure.

Question 4

An autoclave that sterilizes at 121°C for 15 minutes uses which combination of conditions?

Accepted Answer

Moist heat (steam) at 15 psi

Answer

Standard autoclaving uses saturated steam (moist heat) at 15 psi (103 kPa) above atmospheric pressure, achieving 121°C for effective sterilization.

Question 5

A laboratory balance displays 5.003 g when weighing a 5.000 g reference weight. The balance is:

Accepted Answer

Precise but not accurate

Answer

If the balance consistently reads 5.003 g (reproducible), it is precise; however, since it deviates from the true 5.000 g value, it is not accurate.

(MLS) Medical Laboratory Scientist Practice Test

(MLS) Medical Laboratory Scientist Practice Test

MLS Laboratory Equipment & Techniques 3