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How many of the following elements give a characteristic flame test color: Li, Na, K, Be, Mg, Ca, Ba, Cs?

1. 4
2. 5
3. 6
4. 7

Correct answer: 6

Solution

Li: crimson red; Na: golden yellow; K: lilac/violet; Ca: brick red; Ba: apple green; Cs: blue/violet. Be and Mg do NOT give characteristic flame test colors (their ionization energies are too high and the excited states do not emit in the visible range under standard Bunsen flame conditions). Count: Li, Na, K, Ca, Ba, Cs = 6 elements.

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