Question

an isotope represented as s - 34:
has 34 protons.
contains exactly 18 neutrons.
is an isotope of sodium.
must have exactly 18 electrons.
none of the above

Explanation:

Step1: Recall atomic number of sulfur

The atomic number of sulfur (\(S\)) is \(16\). This means the number of protons in sulfur is \(16\). So, the statement "has 34 protons" is wrong.

Step2: Calculate number of neutrons

The mass number is \(34\) (from \(S - 34\)). Using the formula \(mass\ number=protons + neutrons\), we get \(neutrons=mass\ number - protons\). Substituting values (\(protons = 16\), \(mass\ number=34\)), we have \(neutrons=34 - 16=18\). But this is only for a neutral atom. If it is an ion (not specified here), the number of electrons can change.

Step3: Check element identity

\(S\) is sulfur, not sodium (\(Na\)). So, "is an isotope of sodium" is wrong.

Step4: Consider electron - proton relationship

For a neutral atom, \(electrons = protons\). But if it is an ion (e.g., \(S^{2-}\)), \(electrons=protons + 2=16 + 2 = 18\), but the problem does not state it is neutral. So, we cannot be sure it has exactly 18 electrons.

Answer:

none of the above