JEE Main 2024 — Practical Chemistry Question with Solution

The flame test is used to visually determine the identity of an unknown metal or metalloid ion based on the characteristic colour the salt turns the flame of a Bunsen burner. The heat of the flame excites the electrons of the metal ions, causing them to emit visible light.

$$\begin{gathered} {\mathrm{Sr}}^{2+}-\mathrm{Crimson} \mathrm{red} \mathrm{colour} \\ {\mathrm{Cu}}^{2+}-\mathrm{Blue} \mathrm{green} \mathrm{colour} \\ {\mathrm{Ca}}^{2+}-\mathrm{Brick} \mathrm{red} \mathrm{colour} \\ {\mathrm{Ba}}^{2+}- \mathrm{Pale} \mathrm{green} \mathrm{colour} \end{gathered}$$

Hence, the answer is $4$.