Question

which of the following is false for an atom with a high electron affinity?
the atom is more likely to be a non-metal.
the atom is likely to have a low effective nuclear charge.
the atom is likely to have more than 4 valence electrons.
the atom is not likely to exist at a filled or half-filled subshell.

Explanation:

1. Non-metals generally have high electron affinity as they tend to gain electrons to form stable anions, so the first statement is true.
2. A low effective nuclear charge means the nucleus has a weak pull on incoming electrons, which would result in low electron affinity. High electron affinity requires a strong effective nuclear charge to attract additional electrons, so this statement is false.
3. Atoms with more than 4 valence electrons need fewer electrons to reach a full octet, so they have a higher tendency to gain electrons (high electron affinity), making this statement true.
4. Filled or half-filled subshells are stable configurations; atoms with these configurations have little to no tendency to gain electrons (low electron affinity), so atoms with high electron affinity do not have these configurations, making this statement true.

Answer:

The atom is likely to have a low effective nuclear charge.