2(a) Test Observation Inference Add dilute HNO₃ and filter Effervescence observed. Colourless gas evolved which turns lime water milky. CO₂ evolved. Carbonate present. 2(b)(i) Test Observation Inference Add NaOH(aq) dropwise and in excess Light blue precipitate formed, insoluble in excess. Cu²⁺ present. 2(b)(ii) Test Observation Inference Add NH₃(aq) dropwise and in excess Light blue precipitate formed which dissolves in excess to give deep blue solution. Cu²⁺ present. 2(c) Observation: Brown solution obtained after addition of iodine solution. Inference: Starch present. Verified Chemistry Practical Questions 👇🏿

let's verify your observations and inferences.

• 2(a) Add dilute $\text{HNO}_3$ and filter:

  • Observation: Effervescence observed. Colourless gas evolved which turns limewater milky.
  • Inference: $\text{CO}_2$ evolved. Carbonate present.
  • Verification: ✅ Correct. The reaction of a carbonate with an acid produces carbon dioxide gas, which turns limewater milky.

• 2(b)(i) Add $\text{NaOH(aq)}$ dropwise and in excess:

  • Observation: Light blue precipitate formed, insoluble in excess.
  • Inference: $\text{Cu}^{2+}$ present.
  • Verification: ✅ Correct. Copper(II) ions form a light blue precipitate of copper(II) hydroxide with $\text{NaOH}$, which is insoluble in excess $\text{NaOH}$.

• 2(b)(ii) Add $\text{NH}_3\text{(aq)}$ dropwise and in excess:

  • Observation: Light blue precipitate formed which dissolves in excess to give deep blue solution.
  • Inference: $\text{Cu}^{2+}$ present.
  • Verification: ✅ Correct. Copper(II) ions form a light blue precipitate of copper(II) hydroxide with $\text{NH}_3$, which then dissolves in excess $\text{NH}_3$ to form a deep blue solution of the tetraamminecopper(II) complex ion.

• 2(c) Observation: Brown solution obtained after addition of iodine solution. Inference: Starch present.

  • Verification: ❌ Incorrect.
    • Observation: A brown solution obtained after the addition of iodine solution means that the iodine solution's original color (brown/yellow) persists.
    • Correct Inference: Starch is absent. If starch were present, the solution would turn blue-black.