Question

plz it is an emergency...
always take the zero mark of lower meniscus as the starting point for every titration.Give reason​

Answer 1

Answer:

It is not clearly visible and hence it gets difficult to check the phase boundaries.

Explanation:

Here, as we have colourless liquid it is easy to see the boundaries (phase boundary) no matter whether it is convex or concave thus we considered the lower meniscus in the colourless liquid.

IN GENERAL TERM

The meniscus is the curvature of the water surface. The water in the tube gets stuck to the boundaries only.

Therefore : A student must measure at the lowest point.

But in the coloured liquid as here it coloured all the outside area and ultimately it gets difficult to check the phase boundaries thus here it is not possible to measure from lower men.