How does one visualise $DNA$ on an agarose gel?

In the process of recombinant $DNA$ technology, proteins and lipids are removed from the medium by which enzymes, respectively?

Palaeontologists unearthed a human skull during excavation. $A$ small fragment of the scalp tissue was still attached to it. Only a little $DNA$ could be extracted from it. If the genes of the ancient man need to be analysed,the best way of getting a sufficient amount of $DNA$ from this extract is:

What type of method is the $PCR$ technique?

Polymerase chain reaction is most useful in

Which one of the following statements is correct regarding gel electrophoresis?