Question

What is a meniscus? Why is it necessary to know about it when measuring liquids?

Answer 1

Hint :We know that the formation is due to the difference between the forces of attraction (adhesive forces) between the inner surface of the tube and the liquid molecules and the force of attraction (cohesive forces) between the liquid molecules.

Complete Step By Step Answer:
Meniscus: It is a small curve which is obtained between two phases when brought into contact i.e. can say due to capillary action. Meniscus is always a downward facing curve obtained between liquid surface and air. It is basically the test tube with volume markings on it i.e. it is calibrated which can measure volumes accurately if the reader reads that properly.
Rule of meniscus: the reader should always read the cylinder markings where the bottom of the meniscus lies i.e. when we place the graduated cylinder on the flat surface and we obtain a meniscus reading, do read that from the bottom of it. The reader must place his eyes on the same level of the stable liquid and read the meniscus with high accuracy.
The graduated cylinder is one of the most common measuring devices in the field of science used to measure volumes of certain substances. We follow up the rule of meniscus while we read the calibrated graduated cylinder on board.
We all have seen a meniscus for a liquid in the capillary tube, while doing an experiment with a capillary tube in our labs. When we pour a liquid in a tube like container, the top surface of the liquid (that is open to air) obtains a bulge like shape, either directing inwards or outwards.

Note :
Do note that these measurements will take place either in laboratory or on the industrial level; which means it can also have some accuracy and precision measurements because everything measured by a naked eye cannot be theoretically considered correct.