Which ion produces a bright yellow color when subjected to a flame test?

• A. Cu^{2+}
• B. Na^+
• C. K^+
• D. Ca^{2+}

Answer: (B)

Verified step by step guidance

1. Understand that a flame test is used to identify metal ions based on the characteristic color they emit when heated in a flame.
2. Recall that sodium ions (Na^+) produce a bright yellow color in a flame test due to the excitation of electrons and the specific wavelengths of light they emit when returning to the ground state.
3. Recognize that other ions listed, such as Cu^{2+}, K^+, and Ca^{2+}, produce different flame colors: Cu^{2+} often gives a green or blue-green flame, K^+ gives a lilac or light purple flame, and Ca^{2+} gives an orange-red flame.
4. Match the ion to the flame color observed: since the question asks for the ion producing a bright yellow flame, identify Na^+ as the correct ion.
5. Summarize that the bright yellow flame is characteristic of sodium ions (Na^+) due to their unique electron transitions.