The hardest material is diamond. The hardest artificial substance would wurtzite boron nitride. That's basically just man-made diamonds.
<u>Answer:</u> The beta-particle is being released in the reaction and the nucleus is changing from to nitrogen.
<u>Explanation:</u>
Carbon-14 undergoes a radioactive decay by the process of beta-minus decay.
In beta-minus decay, a neutron gets converted to a proton and an electron.
The equation for the beta-minus decay of carbon-14 follows the reaction:

In this reaction beta-particle is being released carrying -1 charge. Another name for this particle is known as electron.
In this decay process, the nucleus is changing from carbon to nitrogen. The property of the nucleus is changing completely as number of protons is getting increased.
The chemical reaction would be written as:
2Na + Cl2 = 2NaCl
Since we are given the amounts of the reactants available for reaction, we have to determine the limiting reactant. And use this amount to calculate for the theoretical yield.
55 g Na ( 1 mol / 22.99 g ) = 2.39 mol Na
67.2 f Cl2 ( 1 mol / 70.9 g ) = 0.95 mol Cl2
Therefore, the limiting reactant would be Cl2 since it is the one consumed completely.
0.95 Cl2 ( 1 mol NaCl / 1 mol Cl2) = 0.95 NaCl produced from the reaction