Answer:
Essentially, a control variable is what is kept the same throughout the experiment, and it is not of primary concern in the experimental outcome. Any change in a control variable in an experiment would invalidate the correlation of dependent variables (DV) to the independent variable (IV), thus skewing the results.
Magnese sulfide would be MnS
Count how many protons there is and search up what symbol has this many protons
Double Replacement Reaction