Question

35. What is the set up used to determine the average atomic mass of Boron in #34?

A. (10 + 11) /2
B. (10 x .20) + (11 x .80)
C. 11 + 10
D. (10 x .20) + (11 x .80) /2

Answer 1

Answer: B

Step-by-step explanation: 2 isotopes of boron are present.

Let percent abundance of B-10 is x

percent abundance of B-11 is (100-x)

Average atomic mass,

`10.80=(x*10+(100-x)*11)/(100)`

`10.80=(10x+1100-11x)/(100)`

`1080=1100-x`

`x=20`