Challenge: balance the equations below A. ___ NaNO3 + ___ PbO → ___ Pb(NO3)2 + ___ Na2O
B. ___ Ca3P2 + ___ H2O → ___Ca(OH)2 + ___ PH3
C. ___Fe2O3 + ___ CO → ___Fe + ___ CO2
D. ___NH3 + ___ O2 → ___ NO2 + ___ H2O
E. ___FeS + ___O2 → ___Fe2O3 + ___SO2
F. ___ C3H8 + ___ O2 → ___ CO2 + ___ H2O

In chemistry, the type of an atom (what element it is) is determined by: a) the number of protons it contains in its nucleus.b) the number of neutrons it contains in its nucleus.c) the number of protons it has in a cloud around the nucleus.d) the number of neutrons it has in a cloud around the nucleus.e) the number of electrons it exchanges with its neighbors.