Neco Model Questions Vol1 2022 Chemistry Question 3

A student performed a series of qualitative tests on three unknown solid samples labelled A, B and C. The observations are recorded in the table below. | Sample | Solubility in water | Conductivity of the aqueous solution | Flame test colour | Additional observation | |--------|---------------------|--------------------------------------|-------------------|------------------------| | A | Soluble (colourless solution) | High (low resistance) | Lilac (characteristic of K⁺) | None | | B | Insoluble | No conduction | Bright white glow when heated in a Bunsen flame; the solid is malleable | Metallic luster | | C | Soluble (colourless solution) | Very low (practically non‑conducting) | No colour | Sweet taste (identifies as a sugar) | Based on the above data, answer the following questions. (a) Classify each sample as having an ionic, metallic or covalent (molecular) type of bonding. (b) Write a plausible chemical formula for each sample. (c) Explain the lilac flame colour observed for Sample A in terms of electron transitions. (d) State one practical application of each type of compound identified in part (a).