Isotopes and percent abundance

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Isotopes of an element have a different number of...

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Neutrons

Front

Rubidium has two common isotopes, ⁸⁵Rb and ⁸⁷Rb. If the abundance of ⁸⁵Rb is 72.2% and the abundance of ⁸⁷Rb is 27.8%, what is the average atomic mass of rubidium?

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85.6 amu

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An isotope has three forms: 10% have a mass of 4 amu, 20% have a mass of 5 amu, and 70% have a mass of 6 amu. What is the average atomic mass?

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6 amu

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Calculate the average atomic mass of silver.

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107.8677amu

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What is the name of the atom pictured here? Options: Nitrogen, Nitrogen-15, Nitrogen-7, Nitrogen-8

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Nitrogen-15

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What is the weighted average of the masses of all naturally occurring isotopes of an element called?

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average atomic mass

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In isotopic notation, what number is on top?

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mass number

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In isotopic notation, what number is on the bottom?

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atomic number

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An unknown element has three isotopes with the following abundances and relative masses: 0.005% (234.04 amu), 0.720% (235.04 amu), 99.275% (238.05 amu). Determine the element from the periodic table. Options: Uranium (#92, Atomic Mass: 238.03 amu), Fluorine (#9, Atomic Mass: 19.00 amu), Mercury (#89, Atomic Mass: 200.59 amu), Polonium (#84, 209 amu).

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Uranium (#92, Atomic Mass: 238.03 amu)

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Element Z has 2 natural isotopes. One isotope has a mass of 15.0 amu and a relative abundance of 30%. The other isotope has a mass of 16.0 amu and a relative abundance of 70%. Estimate the average atomic mass for this one element.

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15.7 amu