Question

The average atomic mass of copper is 63.5u. It exists as two isotopes which are Cu*63 & Cu*65. Cal culate the %age of each atom present in it. *


20% & 80%

75% & 25%

25% & 75%

80% & 20%​

Answer 1

Answer:

25% & 75%

Explanation:

Let the natural abundance of

63

Cu isotope be x%.

The natural abundance of

65

Cu isotope will be 100−x.

The average atomic weight is 63.546 g.

Hence, 100×63.546=63x+65(100−x)

6354.6=63x+6500−65x=6500−2x

2x=145.4

x=72.7≃70

Hence, the natural abundance of the

63

Cu isotope must be approximately 70%.

hope it helps you