What happens when an oxygen atom becomes an oxygen ion ?
(a) It's atomic mass decreases.
(b) It's nucleon number increases.
(c) It's atomic number remains same.
(d) It's mass number increases.
Correct option is:

Question

Accepted Answer

When an oxygen atom becomes an oxygen ion, it undergoes a change in its electron configuration, but its atomic number remains the same. Let's explore why Option 4 is the correct answer and why the other options are incorrect:

1. **Explanation for Option 4 (only (c))**:
   - The atomic number of an element is determined by the number of protons in its nucleus. When an oxygen atom becomes an oxygen ion, it either gains or loses electrons, but the number of protons remains unchanged. Therefore, the atomic number remains the same. This is why Option 4, which states that only (c) is correct, is the right choice.

2. **Why Option 1 (a) and (c) is incorrect**:
   - Statement (a) suggests that the atomic mass decreases. However, the atomic mass is primarily determined by the number of protons and neutrons in the nucleus. Since the conversion of an oxygen atom to an ion involves only the gain or loss of electrons, the atomic mass remains essentially unchanged. Therefore, (a) is incorrect, making Option 1 incorrect.

3. **Why Option 2 (b) and (d) is incorrect**:
   - Statement (b) claims that the nucleon number increases. The nucleon number, or mass number, is the sum of protons and neutrons in the nucleus. Since the ionization process does not affect the nucleus, the nucleon number does not change. Thus, (b) is incorrect.
   - Statement (d) suggests that the mass number increases. As mentioned earlier, the mass number is determined by the protons and neutrons, which remain unchanged during ionization. Therefore, (d) is also incorrect, making Option 2 incorrect.

4. **Why Option 3 (only (d)) is incorrect**:
   - As explained, the mass number does not increase when an oxygen atom becomes an ion because the number of protons and neutrons remains constant. Therefore, Option 3 is incorrect.

In conclusion, the correct answer is Option 4, as the atomic number remains the same when an oxygen atom becomes an oxygen ion, while the other statements do not accurately describe the changes that occur during ionization.