Answer: (4) C-14 to 6-12
Explanation:
Carbon dating is used to estimate the age of wooden trees which use carbon dioxide. Carbon has three naturally occurring isotopes.C-12 and C-13 are stable but C-14 is radioactive. C-14 decays to nitrogen-14 and has a half-life of 5,730 years.
Wooden trees naturally incorporate both the C-12 and C-14 during their lifetimes. When wooden trees die, it stops consuming more of radioactive carbon while the C-14 which is already present in them continues to decay back into nitrogen. With the help of C-12 to C-14 ratio, we can estimate the age of wooden objects.
It must have a charge of zero
That would be 222.0 mm to 4 sig figs
You should have given us a table, but I think my table shouldn't be too different.
Let's put oxidation numbers first.
You would have to know that Mg(s) is a reducing agent and Br2(l) is an oxidizing agent. But it is pretty common knowledge that the halogens will tend to take the electrons and alkali and alkaline earth metals will tend to give up electrons.
Mg is oxidized because it gives up electrons; Br2(l) is reduced because it gains electrons. Since the reaction conforms to what we would expect to <em>naturally</em> (thermodynamically favored) occur, it can take place given that the activation energy is supplied.