The natural abundance of calcium in the earth's crust is 3.4% by mass.How many calcium atoms are present in a 1.50 g sample of the earth's crust? A)6.6 × 10²³atoms B)3.1 × 10²²atoms C)7.7 × 10²⁰atoms D)7.7 × 10²²atoms E)5.1 × 10²⁰atoms

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Quizplus · Accepted Answer

First, calculate the mass of calcium in the sample: 1.50 g × 0.034 = 0.051 g. Then, convert this mass to moles: 0.051 g ÷ 40.08 g/mol (molar mass of calcium) = 0.001272 moles. Finally, convert moles to atoms: 0.001272 moles × 6.022 × 10^23 atoms/mol = 7.7 × 10^20 atoms.

The Natural Abundance of Calcium in the Earth's Crust Is