Question

Which of the following cations is detected by the flame test?

• A. ${N{H}_4}^{+}$
• B. $K^{+}$
• C. ${Mg}^{2+}$
• D. ${Al}^{3+}$

Answer 1

Answer: (B)

$K^{+}$

We use flame tests are used to identify small number of metal ions in compounds. When electrons gain energy and jump into any of the empty orbitals at higher levels then they give a characteristic flame by absorbing the energy.
Here, the correct option is (b).
Only $K^{+}$ cations give flame test while $N{H}_4^{+},M{g}^{2+},A{l}^{3+}$ does not.