If 75.0 of the isotopes of an element have a mass of 39.0 and 25.0% of the isotopes have a mass of 36.0 amu, what is the atomic mass of the element?

Atomic mass of element = 38.25 amu

Explanation:

Let X-39 abundance = 75% and X-36 abundance = 25%

Atomic Mass of element = ∑ wt average contributions of each isotope ...

Wt Avg Contribution = fractional abundance x isotopic mass.    

Isotope      Isotopic Mass (amu)     Fractional Abundance     Wt Avg Contbn

 X-39                   39.00                           0.75                              29.25 amu

 X-36                   36.00                           0.25                                9.00 amu

∑ Wt Avg Contributions = 29.25 amu + 9.00 amu = 38.25 amu

=> Atomic mass of element = 38.25 amu

one state would change   like louisiana to texas. thats a change

explanation:

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.