Which quantities must be conserved in all chemical reactions?
1) mass, charge, density
2)mass, charge, energy
3) charge, volume, density
4) charge, volume, energy

What do electromagnetic waves carry? how are they produced through which media can they move? where do they transfer energy? what do they not transfer? what do mechanical waves carry? how are they produced? through which media can they move? where do they transfer energy? what do they not transfer?