16.H2O (water) and NaCl (salt) are _________ that are in salt water, which is a(n) __________. Water and salt contain the ____________ hydrogen, oxygen, sodium, and chlorine.

Compounds; mixture; elements
Mixture; compounds; elements
Element; compounds; mixture
Compound; elements; compounds

12.The number of _____ determines which element it is.

electrons
protons
positrons
neutrons