Answer:
56.9 amu
Explanation:
Depending on the number of isotopes an element has, the Average atomic mass of isotopes of an element can be calculated using:
(atomic mass of isotope1 × decimal abundance of isotope1) + (atomic mass of isotope2 × decimal abundance of isotope2)
According to this question, two isotopes of element Z were given
- Isotope Z- 56 with atomic mass 56 is 70% abundance. This means that its decimal abundance is 0.70
- Isotope Z- 59 with atomic mass 59 is 30% abundance. This means that its decimal abundance is 0.30
Therefore, average atomic mass of element Z is:
= (56 × 0.70) + (59 × 0.30)
= (39.2) + (17.7)
= 56.9
