D. 18 x 10^23 is the total number of atoms in 1.0 mole of CO2
<span>A small proportion of helium in the crust is helium that was trapped in the Earth when the Earth formed and has not yet escaped. Most helium on Earth, however, forms as a result of alpha decay of uranium and thorium. The emitted alpha particles, once they grab a couple of stray electrons, become helium atoms and can accumulate in gas reservoirs along with things such as methane.</span>
When a metal undergoes a reaction, especially with a nonmetal, you should look for the formation of salts or the formation of precipitates in the case the product is not soluble to water. Metals loses electrons to form positive ions which then reacts to nonmetals that are negatively charged ions.<span />
It is approximately 10 ^ -10
