Question

If bromine atom is available in the form of, say , two isotopes , calculate the atomic mass of bromine atom



please answer it correctly
I have it's answer already but I can't understand it.....
So please explain it in step by step instructions.
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Answer 1

Answer:

The correct answer is = 80.006u

Explanation:

Average atomic mass of Br=[AtomicmassofBr³⁵79 ×percentage + AtomicmassofBr³⁵81 ×percentage]/100

=[79×49.7 + 81×50.3]/100

= 80.006u

Answer 2

the question is incomplete

the right question is:If bromine atom is available in the form of say, two isotopes

35 79Br(49.7%) and

35 81 Br(50.3%). Calculate the average atomic mass of bromine atom.

Solution:

we know the avg atomic mass=( mass1*composition1+mass2*composition2)/total composition

so for given question

avg atomic mass= (79*49.7+81*50.3)/(50.3+49.7)

=(3926.3+4074.3)/100

=8000.6/100

=80 (approx)