Why should antibiotics be used only when prescribed by a certified health professional?

Why should we avoid use of synthetic soft drinks?

Why should the object be moved at constant velocity when we define potential energy ?

Why should we avoid taking antibiotics too often to treat and infection.

We can see things around us only when the light reflected by them reaches our eyes.

When viewing through a compound microscope, our eyes should be positioned not on the eyepiece, but a short distance away from it for best viewing . why ? How much should be that short distance between the eye and eyepiece?

When body is weighted on an ordinary balance we demand that the arm should be horizontal if the weights on the two pans are equal. Suppose equal weights are put on the two pahns, the arm is kept at an angle with the horizontal and released. Is the torque of the two weights about the middle point (point of support) zero? Is the total torque zero? If so, why does the arm rotate and finally become horizontal?

Why did Hershey and Chase use radioactively labelled phosphorous and sulphur only? Would they have got the same result if they use radiolabelled carobon and nitrogen?

Microbes play a dual role when used for sewage treatment as they not only help to retrieve usable water but also generate fuel. Write how this happens?