Metals usually become cations since electrons are negatively charged and when they are lost there are more protons than electrons making a positive net charge in the atom. (cations are positively charged ions while anions are negatively charged ions)
I hope this helps. Let me know if anything is unclear.
The equation that relates both energy and wavelength is:

where e is the energy and lambda is the wavelength.
Therefore, as we can see from this equation, the energy of an electromagnetic wave is inversely related to the wavelength of the electromagnetic wave.
To calculate the mass of Fe formed in a) we get first the limiting reactant between Fe2O3 and CO. Given the masses, the ratio of Fe2O3 is 1.33 while that of CO is 1.67. Hence the limiting reagent is Fe2O3. The mass of Fe formed is 148.98 grams. In b, the needed CO is only 112.04 grams. Hence, the excess is 27. 96 grams.
No, they can have<span> a neutral </span><span>charge</span>