Question

neon has isotopes: ne-20 (90%), ne-21 (9%), ne-22 (1%). calculate its average atomic mass.
a 21.0 amu
b 20.0 amu
c 20.1 amu
d 22.0 amu

Explanation:

Step1: Convert percentages to decimals

$90\% = 0.9$, $9\%=0.09$, $1\% = 0.01$

Step2: Calculate the contribution of each isotope

For Ne - 20: $20\times0.9 = 18$
For Ne - 21: $21\times0.09=1.89$
For Ne - 22: $22\times0.01 = 0.22$

Step3: Find the average atomic mass

$18 + 1.89+0.22=20.11\approx20.1$ amu

Answer:

C. 20.1 amu