select the correct answer. determine the average atomic mass of helium, which has two isotopes having atomic…

select the correct answer. determine the average atomic mass of helium, which has two isotopes having atomic masses 4.0026 amu and 3.0160 amu. the relative abundance of the two isotopes is 99.9999 percent and 0.0001 percent, respectively. a. 1.0066 amu b. 3.0160 amu c. 3.5903 amu d. 4.0026 amu

select the correct answer. determine the average atomic mass of helium, which has two isotopes having atomic masses 4.0026 amu and 3.0160 amu. the relative abundance of the two isotopes is 99.9999 percent and 0.0001 percent, respectively. a. 1.0066 amu b. 3.0160 amu c. 3.5903 amu d. 4.0026 amu

Answer

Explanation:

Step1: Convert percentages to decimals

$99.999%=0.99999$, $0.0001% = 0.000001$

Step2: Use average - atomic - mass formula

The formula for average atomic mass $A=\sum_{i}m_i\times x_i$, where $m_i$ is the atomic mass of isotope $i$ and $x_i$ is the relative abundance of isotope $i$. $A = 4.0026\times0.99999+3.0160\times0.000001$ $A=4.0026\times0.99999 + 3.0160\times10^{- 6}$ $4.0026\times0.99999=4.002559974$, $3.0160\times10^{-6}=0.000003016$ $A=4.002559974 + 0.000003016=4.00256299\approx4.0026$ amu

Answer:

D. 4.0026 amu