Neco Model Questions Vol1 2021 Chemistry Question 3

A student carried out a series of simple tests on four different substances to investigate the nature of the bonding present. The substances were labelled as follows: - Sample A: Sodium chloride (NaCl) solid dissolved in distilled water. - Sample B: Copper(II) sulfate (CuSO₄·5H₂O) solid dissolved in distilled water. - Sample C: Carbon tetrachloride (CCl₄) liquid placed in a clean dry test tube. - Sample D: A small piece of magnesium ribbon placed in dilute hydrochloric acid (0.10 M HCl). The observations recorded are shown in the table below. | Sample | Conductivity of the solution (if any) | Reaction with dilute HCl (if applicable) | Physical state observed | Flame test colour (if performed) | |--------|----------------------------------------|-------------------------------------------|--------------------------|-----------------------------------| | A | Strong (metallic electrode) | No visible reaction | Clear colourless solution| Yellow‑orange (Na) | | B | Strong (metallic electrode) | No visible reaction | Clear blue solution | Blue‑green (Cu) | | C | No conductivity (no solution) | No reaction (liquid unchanged) | Colourless liquid | No flame test performed | | D | Strong (metallic electrode) after 2 min| Vigorous effervescence, solution becomes colourless | Clear colourless solution| No flame test performed | Using the above data, answer the following: