NEON has 2 ISOTOPES of differing mass and in different proportions shown below. Which option demonstrates how we calculate its relative atomic mass (A_(r)) in g/mol {}^20Ne:91% {}^22Ne:9% ((91+9)times (20+22))/(100)=42 ((91+20)times (9+22))/(100)=7.11 ((91times 9)+(20times 22))/(100)=12.6 ((91times 20)+(9times 22))/(100)=20.2

# Explanation:## Step 1:Firstly, recognise we are given two isotopes of Neon (Ne), one with atomic mass 20 (Isotope 20Ne) being 91% abundant and another with atomic mass 22 (Isotope 22Ne) being 9% abundant.## Step 2: The proper formula to calculate the relative atomic mass \( (A_r) \) is weighted average calculation based on the individual isotopes' relative abundance. This is done by multiplying the abundance by the atomic mass and summarize the results of all Isotopes.### Formula: \( A_r = \sum \text{iso}_\text{i} (\text{Abundance}_\text{i} × \text{Mass}_\text{i}) \) * The above calculation should be performed for all the isotopes, i.e 'i'.## Step 3:Replace values of the atomic mass and abundance of each considered Neon isotope into the formula.# Answer :Replacing the values into the formula we'll have:\( A_r = (0.91 × 20) + (0.09 × 22) \)So let's compute this: Thus, the relative atomic mass (or 'molar mass') of Neon (Ne) is .