$7.$ Determine the atomic mass of each element, given the isotopic composition.

Show your work for full credit $(1$pt each$).$

a$.$ Lithium, which is $92\mathrm{.}4\%$ Lithium$-7($mass $7\mathrm{.}016$u$)$ and $7\mathrm{.}60\%$

Lithium$-6($mass $6\mathrm{.}015$u$).$

b$.$ Oxygen, which is $99\mathrm{.}76\%$ Oxygen$-16($mass $15\mathrm{.}995$u$),0\mathrm{.}038\%$

Oxygen$-17($mass $16\mathrm{.}999$u$),$ and $0\mathrm{.}203\%$ Oxygen$-18($mass $17\mathrm{.}999$u$)$

$8.$ What is the average mass of a single Neon atom found in nature $(1$pt$)?$

$9.$ Chlorine consists of two naturally occurring isotopes, Chlorine$-35$ and

Chlorine$-37.$ Which isotope has the greater abundance? Explain how you

determined your answer $(1$pt$).$