Answer:
46.96 amu
Explanation:
Isotopes are different kinds of same elements. The difference between two isotopes of the same element is the number of neutrons.
To get the relative atomic mass, we take into consideration the masses of the different isotopes. This is done by multiplying their abundances by their masses. They are then added together to get the relative atomic mass of the element.
Let the isotopic mass of 47Z be x
45.36 = [80/100 * 44.96] + [20/100 * x]
45.36 = 35.968 + 0.2x
0.2x = 45.36 - 35.968
0.2x = 9.392
x =9.392/0.2 = 46.96 amu