Neco Model Questions Vol1 2019 Chemistry Question 1

A student performed a flame test on three unknown solid samples (A, B and C) using a Bunsen burner. The observed flame colours were recorded as follows: - Sample A: bright crimson - Sample B: intense yellow‑orange - Sample C: pale violet The student also carried out the same test on four reference metal salts whose dominant flame colours are known: - Sodium chloride (NaCl) – bright yellow‑orange - Calcium chloride (CaCl₂) – brick‑red - Potassium chloride (KCl) – pale violet - Strontium chloride (SrCl₂) – bright crimson The student is required to: (a) Identify the metal ion present in each unknown sample by comparing the flame colours with the reference salts. (b) Using the identified metal ion, write the electronic configuration of the outermost (valence) shell for each metal. (c) From the electronic configurations, deduce the group number of each metal in the periodic table and explain how the flame colour is related to the electronic transitions involved.