Why is it important for scientists to replicate each other’s experiments?

It is very important for scientists to replicate each other experiment because this will help to determine if important scientific results are repeatable. The correct option is Scientific results presented by a scientist should be reproducible anywhere in the world, without this, the results can not be accepted as theory.

Protons have a positive charge and, collectively, give an element its atomic number.

The correct answer is  "c".  it is "c" because melting is an endothermic change, and endothermic get's energy from surroundings.