Use the following additional information to answer the next question. mass of gallium -69 nucleus=68.925580u mass of neutron=1.008665u mass of proton=1.007276u 1. The mass defect of gallium-69 is A. 0.619523 u B. 0.629246 u C. 0.650000 u D. 0.595420 u

Here's how to calculate the mass defect and determine the correct answer:<br /><br />1. **Determine the number of protons and neutrons:** Gallium-69 has an atomic number of 31 (meaning 31 protons) and a mass number of 69. Therefore, it has 69 - 31 = 38 neutrons.<br /><br />2. **Calculate the theoretical mass:** This is the mass if the nucleus were simply the sum of its individual protons and neutrons.<br /> Theoretical mass = (number of protons * mass of proton) + (number of neutrons * mass of neutron)<br /> Theoretical mass = (31 * 1.007276 u) + (38 * 1.008665 u)<br /> Theoretical mass = 31.225556 u + 38.32927 u<br /> Theoretical mass = 69.554826 u<br /><br />3. **Calculate the mass defect:** This is the difference between the theoretical mass and the actual mass.<br /> Mass defect = Theoretical mass - Actual mass<br /> Mass defect = 69.554826 u - 68.925580 u<br /> Mass defect = 0.629246 u<br /><br />Therefore, the correct answer is **B. 0.629246 u**<br />