IF AN EGG IS PUT IN A BEAKER OF WATER IT SINKS.ON DISSOLVING A LOT OF SALT IN THE WATER THE EGG BEGINS TO RISE AND THEN FLOATS.WHY?

Egg has density higher than water, so it sinks when put in a beaker containing water.

 

When salt is added to water, the density  of solution so formed increases. This density is greater than that of the egg. Hence, more upthrust is exerted on egg which makes it to rise up in the solution and then float.