These go beyond the standard exercise into genuine HOTS (Higher Order Thinking Skills) territory — reactivity-series reasoning, extraction logic, and identification-style problems with fresh numbers/scenarios. See the standard-level Solutions first if you haven’t already.
Extra Questions (HOTS Level): Metals and Non-metals (Class 10 Science Chapter 3)
Q1. Three metals P, Q and R are such that P displaces Q from its salt solution, and Q displaces R from its salt solution, but R does not displace P. Arrange P, Q and R in decreasing order of reactivity, and justify.
Since P displaces Q, P is more reactive than Q. Since Q displaces R, Q is more reactive than R. Since R cannot displace P, this is consistent (R is the least reactive).
Order: P > Q > R.
Q2. A student drops a strip of zinc into a solution of copper sulphate and a strip of copper into a solution of zinc sulphate. Predict what happens in each case, with a reason and equation for any reaction.
Zinc is more reactive than copper, so zinc in copper sulphate solution displaces copper: Zn + CuSO₄ → ZnSO₄ + Cu (blue colour of the solution fades, reddish-brown copper deposits).
Copper is less reactive than zinc, so copper placed in zinc sulphate solution shows no reaction.
Q3. Assertion-Reason: Assertion (A): Ionic compounds generally have high melting and boiling points. Reason (R): Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions. Choose the correct option: (i) Both A and R are true, and R is the correct explanation of A. (ii) Both A and R are true, but R is not the correct explanation of A. (iii) A is true, R is false. (iv) A is false, R is true.
A considerable amount of energy is needed to break the strong electrostatic forces holding the ions in a rigid lattice together, which directly causes the high melting/boiling points.
Answer: (i).
Q4. An unknown metal X does not react with cold water or hot water, but reacts vigorously with steam to form an oxide and hydrogen gas. Identify the reactivity zone of X on the reactivity series and name one real metal that fits this description.
Metals that don’t react with cold/hot water but do react with steam sit in the middle of the reactivity series — more reactive than lead/copper/silver/gold, but less reactive than sodium/potassium/calcium (which react with cold water) or magnesium (which reacts with hot water).
Example: aluminium, zinc or iron — e.g. 3Fe + 4H₂O → Fe₃O₄ + 4H₂.
Q5. Explain why ionic compounds conduct electricity in the molten state and in aqueous solution, but not in the solid state.
In the solid state, the ions are locked in fixed positions in a rigid crystal lattice and cannot move to carry charge. On melting or dissolving in water, the lattice breaks down and the ions become free to move, so they can carry electric current.
Q6. A metal carbonate ore of a reactive metal is being processed to extract the pure metal. Outline, in order, the three broad steps typically used, and explain why the ore is not reduced directly.
Broad steps: (1) concentration of the ore (removing impurities like sand/rock), (2) conversion of the concentrated ore to its oxide (calcination, since carbonates decompose to oxides on strong heating), (3) reduction of the oxide to the free metal (by a reducing agent, or electrolysis for very reactive metals).
The ore is not reduced directly because oxides are generally much easier and more economical to reduce to the metal than carbonates — converting to the oxide first is the standard, energy-efficient route.
Q7. Two test tubes contain dilute HCl. Zinc granules are added to one, and copper turnings to the other. Predict the observation in each, and write any equation.
Zinc is above hydrogen in the reactivity series, so it reacts with dilute HCl, displacing hydrogen gas with effervescence: Zn + 2HCl → ZnCl₂ + H₂↑.
Copper is below hydrogen in the reactivity series, so no reaction occurs with copper turnings.
Related: Solutions | Extra Questions | Revision Notes | Formulas Handbook | Class 10 Science Book
