Prove that the solution given to you in the test tube is sodium iodide.

We are given a solution, presumably sodium iodide, chemical formula NaI. We need to prove that this is exactly the case. For this, we need to conduct a qualitative reaction. Sodium iodide can be determined by performing a reaction such as interaction with bivalent lead nitrate. We observe the reaction, if the solution is really sodium iodide, then as a result of the reaction, a salt of lead iodide is formed, which will precipitate a golden color and sodium nitrate salt. The molecular equation of the reaction can be written as follows:
2 NaI + Pb (NO3) 2 = PbI2 + 2 NaNO3.