On a mission to a newly discovered planet, an astronaut finds copper abundances of 69.15 % for 63cu and 30.85 % for 65cu. what is the atomic mass of copper for this location? the mass of 63cu is 62.9300 amu . the mass of 65cu is 64.9200 amu .

The relative atomic mass is the weighted average mass of elements relative to 1/12th the mass of a 12-C atom.
Isotopes are atoms of the same element with different masses , in other words different numbers of neutrons.
Relative atomic mass =sum of (mass x percentage )
R.a.m = 62.9300 x 69.15% + 64.9200 x 30.85%
= 43.52 + 20.03
= 63.55 amu

The answer is c. 320 g

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