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Metals & Non-metals

General Science · Chemistry

Useful for: Railway RRB, OSSC RHT — Regular High School Teacher, OSEPA Upper Primary — Science, OSSC Science, OSSSC Govt TGT Science — CBZ, OSSSC Govt TGT Science — PCM, SSB Lecturer (Degree Colleges), SSB TGT CBZ

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SSB TGT PCM

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Overview

Metals are generally lustrous, malleable conductors; non-metals are mostly brittle insulators; reactivity decides displacement.

Key points

Reactivity series: K > Na > Ca > Mg > Al > Zn > Fe > Pb > (H) > Cu > Hg > Ag > Au.
A more reactive metal displaces a less reactive one from its salt solution.
Mercury is a liquid metal; bromine is a liquid non-metal.
Graphite (a non-metal) conducts electricity.
Alloys: brass (Cu + Zn), bronze (Cu + Sn), steel (Fe + C), stainless steel (Fe + Cr + Ni).

Explanation

Rusting of iron needs oxygen and water; galvanising coats iron with zinc.
Sodium is stored in kerosene because it reacts with air and water.
Gold and platinum are least reactive (noble metals).
Aluminium forms a protective oxide layer.

Step by step

Identify the concept or law involved.
Recall the definition, unit or formula.
Check units and the direction of the effect before choosing.

Examples

Brass is an alloy of copper and zinc.
The liquid non-metal is bromine.
Iron placed in copper sulphate solution displaces copper.

Traps and advanced points

Trap: Calling bronze Cu + Zn.
Trap: Thinking copper displaces iron.
Trap: Forgetting graphite conducts.

Quick revision

Reactivity series.
Alloy compositions.
Hg liquid metal, Br liquid non-metal.

Practice MCQs

Static-GK drill: Lemon juice is rich in which acid?
1. Acetic acid
2. Hydrochloric acid
3. Oxalic acid only
4. Citric acid
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Answer: (d) Citric acid. Lemon juice is rich in Citric acid.
Which option correctly answers this General Science check: symbol K represents?
1. sodium
2. mass per unit volume
3. potassium
4. None of these
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Answer: (c) potassium. K comes from Latin kalium.
The most reactive metal among these is —
1. gold
2. copper
3. potassium
4. iron
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Answer: (c) potassium. K is at the top of the reactivity series.
A liquid metal at room temperature is —
1. mercury
2. bromine
3. sodium
4. aluminium
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Answer: (a) mercury. Mercury; bromine is a liquid non-metal.
Which non-metal conducts electricity?
1. graphite
2. iodine
3. phosphorus
4. sulphur
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Answer: (a) graphite. Graphite has free electrons.
Brass is an alloy of —
1. iron and chromium
2. copper and tin
3. copper and zinc
4. iron and carbon
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Answer: (c) copper and zinc. Brass = Cu + Zn.
Bronze is an alloy of —
1. iron and nickel
2. aluminium and copper
3. copper and tin
4. copper and zinc
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Answer: (c) copper and tin. Bronze = Cu + Sn.
Sodium is stored in kerosene because it —
1. reacts vigorously with air and water
2. is a liquid
3. is a noble metal
4. is very heavy
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Answer: (a) reacts vigorously with air and water. Kerosene keeps it away from air and moisture.
Galvanising coats iron with —
1. tin
2. zinc
3. copper
4. silver
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Answer: (b) zinc. Zinc protects iron from rusting.
Iron displaces copper from copper sulphate because iron is —
1. less reactive
2. more reactive
3. a non-metal
4. a noble metal
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Answer: (b) more reactive. More reactive metals displace less reactive ones.