Acetic acid solution turns

Four student A, B, C and D traced the paths of incident ray and the emergent ray by fixing pains P and Q for incident ray and pains R and S for emergent ray for a ray of light passing through a glass slab.

The correct emergent ray was traced by the student:

To show that zinc is a more active metal than copper, the correct procedure is to

A student was given two permanent slides, one of binary fission in amoeba and other of budding in yeast. He was asked to identify any one difference in the nucleus of the two. One such difference, he indentified correctly was

Raisins are wiped off gently before final weighing with help of