Eansider the following atoms in which X represents the chemical symbol of the ment: \( \square \) Which atoms are isotopes? \( \square \) Which atoms have the same mass number? \( \square \) What atoms have the same number of protons? What atoms have the same number of neutrons? 1. \( { }_{8}^{17} X \) and \( { }_{9}^{16} X \) 2. \( { }_{9}^{16} X,{ }_{10}^{18} X \) and \( { }_{8}^{18} X \) 3. \( { }_{8}^{16} X,{ }_{8}^{17} X \) and \( { }_{8}^{18} X \) 4. \( { }_{8}^{16} X \) and \( { }_{9}^{16} X ;{ }_{10}^{18} X \) and \( { }_{8}^{18} X \) 5. \( { }_{8}^{16} X \) and \( { }_{10}^{18} X \)

We start by writing an atom in the form \[ { }_{Z}^{A} X, \] where: - \( Z \) is the atomic number (number of protons), - \( A \) is the mass number (total number of protons and neutrons), and - the number of neutrons is given by \( A - Z \). The atoms given in the options are: 1. \( { }_{8}^{17} X \) 2. \( { }_{9}^{16} X \) 3. \( { }_{16}^{8} X \) is not given directly, but we have variants with mass numbers 16, 17, and 18; we list all atoms based on the options: - \( { }_{8}^{16} X \) - \( { }_{8}^{17} X \) - \( { }_{8}^{18} X \) - \( { }_{10}^{18} X \) We now calculate the neutrons for each atom: 1. For \( { }_{8}^{17} X \): \[ \text{Neutrons} = 17 - 8 = 9. \] 2. For \( { }_{9}^{16} X \): \[ \text{Neutrons} = 16 - 9 = 7. \] 3. For \( { }_{8}^{16} X \): \[ \text{Neutrons} = 16 - 8 = 8. \] 4. For \( { }_{10}^{18} X \): \[ \text{Neutrons} = 18 - 10 = 8. \] 5. For \( { }_{8}^{18} X \): \[ \text{Neutrons} = 18 - 8 = 10. \] Now, we review the choices for which pair (or group) of atoms has the same number of neutrons: 1. \( { }_{8}^{17} X \) and \( { }_{9}^{16} X \): They have 9 and 7 neutrons, respectively. (Not equal.) 2. \( { }_{9}^{16} X \), \( { }_{10}^{18} X \) and \( { }_{8}^{18} X \): Their neutron numbers are 7, 8, and 10 respectively. (Not equal.) 3. \( { }_{8}^{16} X \), \( { }_{8}^{17} X \) and \( { }_{8}^{18} X \): Their neutron numbers are 8, 9, and 10 respectively. (Not equal.) 4. Two pairs: - \( { }_{8}^{16} X \) and \( { }_{9}^{16} X \): Neutrons are 8 and \(16-9=7\). - \( { }_{10}^{18} X \) and \( { }_{8}^{18} X \): Neutrons are 8 and 10. (Neither pair has equal neutron numbers.) 5. \( { }_{8}^{16} X \) and \( { }_{10}^{18} X \): Their neutron numbers are \[ { }_{8}^{16} X: 16 - 8 = 8, \quad { }_{10}^{18} X: 18 - 10 = 8. \] Both have 8 neutrons. Thus, only option 5 has atoms with the same number of neutrons. \[ \boxed{\text{Option 5}} \]