B because A is for radios of course and C is thermal energy and D is radioactive
The average atomic mass of tellurium, calculated from its eight isotopes (Te-120 (0.09%), Te-122 (2.46%), Te-123 (0.87%), Te-124 (4.61%), Te-125 (6.99%), Te-126 (18.71%), Te-128 (31.79%), and Te-130 (34.48%)) is 127.723 amu.
The average atomic mass of Te can be calculated as follows:

Where:
m: is the mass
%: is the abundance percent
Knowing all the masses and abundance values, we have:

To find the <u>average atomic mass</u> we need to change all the <u>percent values</u> to <u>decimal ones</u>

Therefore, the average atomic mass of tellurium is 127.723 amu.
You can find more about average atomic mass here brainly.com/question/11096711?referrer=searchResults
I hope it helps you!
Explanation:
The given data is as follows.
Refractive index of mixture = 1.456
Refractive index of hexane = 1.375
Refractive index of toulene = 1.497
Let mole fraction of hexane =
and, mole fraction of toulene =
Also, 
or, 
Hence, calculate the mole fraction of hexane as follows.
refractive index mixture= mole fraction hexane × ref index hexane + mole fraction toluene × ref index toluene.
1.456 = 
1.456 = 
0.081 = 
= 
= 0.66
Since, 
= 1 - 0.66
= 0.34
Thus, we can conclude that mole fraction of hexane in your sample is 0.34.