Question

The device used for measuring the quality of milk is ________
(a) Respirometer
(b) Sphygmomanometer
(c) Lactometer
(d) Anemometer

Answer 1

Hint: Good-quality raw milk should be free from debris and sediment. It should be free abnormal odour and colour; low in the bacterial count and should have normal composition and acidity. This is measured by a device that can measure the relative density of milk to determine its purity.

Complete step by step answer:
The quality of raw milk is the determining factor of the quality of milk products. The quality of milk is measured using a type of hydrometer called the lactometer.

Additional Information:
- A hydrometer is a type of instrument that measures the relative density of liquids based on buoyancy. They are generally calibrated and graduated with one or more scales like specific gravity.
- Hydrometers are calibrated for different purposes.
For example-A lactometer for measuring the density or creaminess of milk which helps in determining the purity of milk.

- The specific gravity of milk does not give a conclusive indication of its composition because milk contains a variety of substances that are either denser or lighter than water.
- Lactometer is graduated into a hundred parts.
- Milk is poured into the tube and allowed to stand until the cream is formed and then the depth of the cream deposit is measured in degrees which determines the quality of the milk.
- If the milk sample is pure, the lactometer floats and the lactometer sinks if the sample is adulterated or impure.
- A respirometer on the other hand is a device used to measure the rate of respiration in a living organism by measuring the rate of exchange of oxygen and carbon dioxide at a given time.
- A sphygmomanometer is a device that is used to measure the blood pressure of an individual at a given point in time. Blood pressure is the lateral pressure that flowing blood exerts on the walls of the vessels.
- An anemometer is a piece of meteorological equipment that is used to measure the wind speed and direction.
None of the above devices are a type of hydrometer and do not help in measuring the purity of milk.

So, the answer is, “Lactometer”.

Note: Hydrometers use the Archimedes' principle.
- So, the lower the density of the fluid, the deeper a hydrometer of a given weight sinks, and the stem is then calibrated to give a reading.
- Higher the density of the liquid, the lesser the hydrometer sinks.