Which instrument is used to determine the concentration of the prepared anti-freeze solution?

• A. Refractometer
• B. Multimeter
• C. Pitot gauge
• D. Tachometer

Answer: (A)

Determining the concentration of an anti-freeze solution relies on measuring how light bends as it passes through the liquid. A refractometer directly measures this refractive index and, with a calibrated scale, shows the percent glycol (the antifreeze concentration). You put a small drop on the prism, close the cover, and read the scale, using temperature compensation if needed because refractive index shifts with temperature. The other instruments measure things unrelated to concentration: a multimeter checks electrical parameters, a Pitot gauge measures flow pressure, and a tachometer tracks rotational speed. So the refractometer is the appropriate tool for gauging anti-freeze concentration.