Which body systems would be involved in sledding?

How are mutations continually being generated in a population (what are some of the causes of mutatuions? ) explain

Me the formula cacl2 represents the compound

Which best describes the nucleus of an atom a. it is where all of the particle s of the atom are located b. it is the negatively charged part of the atom c. it is where the electrons and the protons are located d. it is the part of the atom with the greatest mass