To solve for the number of moles, we simply have to use the Avogadros number which states that there are 6.022 x 10^23 molecules per mole. Therefore:
number of moles = 6.67 X 10^40 chlorine molecules / (6.022 x 10^23 molecules / mole)
number of moles = 1.108 x 10^17 moles
<h2><u>Answer</u> :</h2>
The most appropriate option is :

Since, they are the most abundant elements found in Earth's Crust.

Answer:
The concentration of hydrochloric acid would be estimated to be less.
Explanation:
This is because, the hydroxyl ions from water react with the hydrogen ions from the hydrochloric acid, hence decreasing the moles of hydrogen ions which lowers the acidic strength of Hydrochloric acid.
Answer:
C. The balloon with CH4 has the same moles of gas molecules as the balloon with H2
Explanation:
Based on combined gas law, gases under the same pressure, temperature and volume have the same number of moles. With this information we can say the rigth statement is:
<h3>C. The balloon with CH4 has the same moles of gas molecules as the balloon with H2</h3>