Class 10 · Science · Chapter 3: Metals and Non-metals
Bihar Board · NCERT · CBSE
Only board questions that already carry a verified year are listed BSEB annual exam questions (previous years) and questions from the board's official model set (marked separately, not an annual exam). No year is guessed. Answers are written by Study With Me, not an official answer key.
← Chapter 3: Metals and Non-metals — full notes, questions
Which of the following gases is formed when zinc reacts with dilute hydrochloric acid?
Correct answer: (B) H2
Metal + dilute acid → salt + hydrogen (lesson 7).
An ore of zinc is—
Correct answer: (D) Zinc blende
Zinc blende (ZnS) is the sulphide ore of zinc; it is roasted to ZnO. Bauxite = aluminium, cinnabar = mercury.
The metal which dissolves only in aqua regia is—
Correct answer: (C) Au
Aqua regia = conc. HCl : conc. HNO₃ = 3 : 1. It dissolves gold (Au) and platinum, which neither acid can do alone.
Which of the following is not an ionic compound?
Correct answer: (B) CO
CaCl₂ and KCl are ionic (metal + non-metal). In CO both are non-metals — electrons are shared, no ions form. Note: HCN is not ionic either; two options look correct in the paper, so we have taken the most direct answer, (b) CO.
The hardest natural substance is—
Correct answer: (D) Diamond
Diamond, an allotrope of carbon, is the hardest natural substance, with very high melting and boiling points (lesson 3, exceptions to Table 3.1).
Which of the following are electronegative?
Correct answer: (A) Non-metals
Non-metals gain electrons to form anions — electronegative. Metals lose electrons to form cations — electropositive.
Which of the following pairs represents a single displacement reaction?
Correct answer: (D) AgNO3
Copper is more reactive than silver, so it displaces Ag. In the other pairs the metal is less reactive.
Cuprite is an ore of which of the following metals?
Correct answer: (C) Cu
Cuprite = Cu₂O, an oxide ore of copper.
Which of the elements shown by these symbols (mass number/atomic number) is a metal?
Correct answer: (B) B (24/12)
Atomic number 12 = magnesium (2,8,2) — 2 outer electrons, a metal. 9 = fluorine, 6 = carbon, 8 = oxygen — non-metals.
What is the process of roasting?
Roasting: heating a sulphide ore strongly in excess air to change it into its oxide. Example — zinc blende:
The oxide is then reduced with carbon: ZnO(s) + C(s) → Zn(s) + CO(g)
Why do metals have a tendency to lose electrons and form cations?
Differentiate between metals and non-metals on the basis of physical and chemical properties.
Physical properties
| Basis | Metals | Non-metals |
|---|---|---|
| Lustre | Lustrous (metallic lustre) | Mostly dull (exception: iodine) |
| Malleability/ductility | Beaten into sheets, drawn into wires | Brittle, neither |
| Conduction | Good conductors of heat and electricity | Poor conductors (exception: graphite) |
| State | Solid (exception: mercury is liquid) | Solid or gas (bromine is liquid) |
| Sonority | Sonorous | Not sonorous |
Chemical properties
| Basis | Metals | Non-metals |
|---|---|---|
| Ions | Lose electrons → cations | Gain electrons → anions |
| Oxides | Basic (Al₂O₃, ZnO amphoteric) | Acidic or neutral |
| Dilute acids | Many displace H₂ | Do not displace H₂ |
| With hydrogen | — | Form hydrides |
Examples: 2Mg + O2 → 2MgO (basic) · S + O2 → SO2 (acidic)
