Question

an isotope has three forms. 30% have a mass of 4 amu, 20% have a mass of 5 amu and 50% have a mass of 3 amu. average atomic mass will be closest to

Explanation:

Step1: Calculate contribution of each isotope

For the isotope with mass \(4\) amu and abundance \(30\% = 0.3\), its contribution is \(4\times0.3\).
For the isotope with mass \(5\) amu and abundance \(20\%= 0.2\), its contribution is \(5\times0.2\).
For the isotope with mass \(3\) amu and abundance \(50\% = 0.5\), its contribution is \(3\times0.5\).

Step2: Sum up the contributions

The average atomic mass \(M\) is given by the formula \(M=(4\times0.3)+(5\times0.2)+(3\times0.5)\).

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Answer:

\(4\) amu (since \(3.7\) amu is closest to \(4\) amu among the given options)