4.4 HW Avg. Atomic Mass

The element Eu occurs naturally as a mixture of 47.82% ¹⁵¹Eu, whose mass is 150.9 amu and 51.18% ¹⁵³Eu, whose mass is 152.9 amu. Calculate the average atomic mass of Eu.

• 1519.4 amu

• 15.194 amu

• 151.97 amu

• 151.94 amu

Three isotopes of magnesium occur in nature. Their abundances and masses are listed below. Use this information to calculate the average atomic mass of magnesium.

• 24.31 amu

• 243.1 amu

• 24310 amu

• 18.88 amu

Naturally occurring chlorine consists of two isotopes: 75.53% of the atoms in a sample are ³⁵Cl, mass = 34.96885 amu, and the other 24.47% are ³⁷Cl, mass = 36.96590 amu. Calculate the average atomic mass of chlorine.

• 354.60 amu

• 35.46 amu

• 3.546 amu

• 0.3456 amu

Naturally occurring silicon consists of three isotopes with the abundances indicated below. From the masses and relative abundances of these isotopes, calculate the average atomic mass of naturally occurring silicon.

• 0.2809 amu

• 28.09 amu

• 280.9 amu

• 6.831 amu

Find the average atomic mass of silver if 51.83% of the silver atoms are ¹⁰⁷Ag with a mass of 106.905 amu and the rest are ¹⁰⁹Ag with a mass of 108.905 amu.

• 55.41 amu

• 52.46 amu

• 10.787 amu

• 107.87 amu