Metals and Non Metals — Karnataka (SSLC) Class 10 Science Solutions (Free)
Free step-by-step Karnataka (SSLC) Class 10 Science solutions for "Metals and Non Metals" — important questions with detailed answers, download PDF for board exam preparation.
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Metals and Non Metals — Textbook Questions Answered (7)
Q1: Define metals and non-metals. List three physical properties that distinguish them.
Metals: elements with 1-3 valence electrons, lose electrons to form cations. Non-metals: elements with 4-8 valence electrons, gain/share electrons. Three properties: 1) Lustre: metals shiny, non-metals dull. 2) Malleability: metals can be hammered into sheets, non-metals brittle. 3) Conductivity: metals conduct heat/electricity, non-metals do not (except graphite).
Q2: What is reactivity series of metals? Arrange Cu, Zn, Fe, Al in order of reactivity.
Reactivity series: arrangement of metals by their tendency to lose electrons; more reactive metals are at top. Order (most to least reactive): Al > Fe > Zn > Cu. Al is most reactive (loses electrons easily), Cu is least reactive. This series predicts displacement reactions: a more reactive metal displaces a less reactive one from its salt solution.
Q3: What happens when metals react with oxygen? Give two examples with equations.
Metals react with oxygen to form metal oxides (oxidation). Examples: 1) 2Mg + O2 = 2MgO (burns with bright light, white powder forms). 2) 4Fe + 3O2 = 2Fe2O3 (brown/red powder, requires heating). Less reactive metals like Cu form oxide slowly: 2Cu + O2 = 2CuO (requires heating, turns black). Reactivity affects speed and intensity.
Q4: Describe corrosion of iron and how it is prevented.
Corrosion = gradual destruction of metal by reaction with environment (O2, H2O, CO2). Iron rusting: 4Fe + 3O2 + 6H2O = 4Fe(OH)3 (brown/orange precipitate). Prevention: 1) Oiling/greasing (prevents water contact). 2) Galvanization (zinc coating protects). 3) Painting (prevents air/water access). 4) Alloys (stainless steel resists corrosion). Rusting is an expensive problem in construction.
Q5: Explain extraction of metals from ores. Name the methods for extraction of iron and aluminum.
Extraction = process of obtaining metals from their ores. Iron: extracted by reduction of iron oxide with carbon monoxide in blast furnace at high temperature (Fe2O3 + 3CO = 2Fe + 3CO2). Aluminum: extracted by electrolysis of molten aluminum oxide in presence of cryolite as flux (electrical energy splits Al2O3 = 2Al + 3/2 O2). Electrolysis is more expensive due to high energy needs.
Q6: What is an alloy? Give three examples and their uses.
Alloy = mixture of two or more elements where at least one is a metal; has different properties from pure metal. Examples: 1) Brass (Cu + Zn): used for musical instruments, decorative items. 2) Bronze (Cu + Sn): used for sculptures, bells, bearings. 3) Steel (Fe + C): used for buildings, bridges, tools (stronger than pure iron). Alloys are harder, more resistant to corrosion than pure metals.
Q7: Why are non-metals generally poor conductors of electricity? Name one exception.
Non-metals are poor conductors because their valence electrons are tightly bound; they don't have free electrons to carry current. Exception: Graphite (form of carbon) is a good conductor due to its layered structure with delocalized electrons between layers. Graphite is used in electrodes, pencil leads, and industrial applications. This makes graphite unique among non-metals.
Related
- NCERT Solutions: Metals and Non Metals — the CBSE version of this same topic.
- Chemical Reactions and Equations — more Karnataka (SSLC) Class 10 Science.
- Acids Bases and Salts — more Karnataka (SSLC) Class 10 Science.
- Carbon and Its Compounds — more Karnataka (SSLC) Class 10 Science.
- Periodic Classification of Elements — more Karnataka (SSLC) Class 10 Science.
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