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The atomic weight of Cu is 63.546. There...

The atomic weight of `Cu` is `63.546`. There are only two naturally occurring isotopes of copper `.^(63)Cu` and `.^(65)Cu`. The natural abundance of the`.^(63)Cu` isotope must be approximately.

A

`10%`

B

`30%`

C

`50%`

D

`72.7%`

Text Solution

Verified by Experts

The correct Answer is:
D
`.^(63)Cu" ".^(65)Cu`
`%` abundance `x" "100-x`
Avg mass `=(M_(1)x_(1)+M_(2)x_(2))/(x_(1)+x_(2))`
`63.546 = (63xx x + 65(100-x))/(100)`
`6354.6=63x+6500-65x`
`2x = 145.4 rArr x =70%` .
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