What happens to the composition of an atom to cause it to become positively or negatively charged?

Can someone explain to me how to do this problem ?

What is meant by the statement" the melting poin of glycerine is 13 degree celsius

What must be the same for any two resistors that are connected in series ? a. the potntial diffrence across each b. the rate at which charge moves through each c. the rate at which energy is used by each d. the resistance to the flow of charge of each