The last one. A bond of two or more of the same element.
Because it is a solid material, it is known as a dry lubricant. This is useful inapplications<span> where “wet” lubricants, such as oil, cannot be </span>used<span>. </span>Graphite<span> is the only non-metal element that is a good conductor of electricity. Natural </span>graphite<span> is </span>used <span>mostly in what are called refractory </span><span>applications</span>
CO2 goes on the bottom and O2 on the top.
There is 213 units i believe hope so