| 1. | Silver atom has two known isotopes existing in nature as 51.82 % 107Ag (atomic mass: 106.9041 u) and 48.18 % 109Ag (atomic mass: 108.9047 u) Calculate the atomic weight of Silver. |
| Answer: 107.868 u |
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| 2. | There are two known isotopes of Iridium atom: 191Ir with a mass of 190.9609 u and 193Ir which has a mass of 192.9633 u. The atomic weight of Iridium atom is 192.2164. What is the percentage occurrence in nature of 191Ir? What is the percentage occurrence in nature of 193Ir? |
| Answer: 37.3% of 191Ir and 62.7% of 193Ir. |
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| 3. | Carbon has an atomic weight of 12.011. Its isotopes exist in nature in the following proportions: 98.89% of 12C, 1.11% of 13C. One of its isotope, 12C, has a mass of 12 u. What is the mass of the other isotope? |
| Answer: 12.991 u |
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