Chapter 3: Metals and Non-metals
Class 10 Science · MCQs with answers
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Which metal is a liquid at room temperature?
- (A) Sodium
- (B) Iron
- (C) Mercury
- (D) Aluminium
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Correct answer: (C) Mercury
Explanation: Mercury is the only metal that is a liquid at room temperature.
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Which non-metal is a liquid at room temperature?
- (A) Iodine
- (B) Bromine
- (C) Sulphur
- (D) Carbon
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Correct answer: (B) Bromine
Explanation: Bromine is the non-metal that is liquid at room temperature. Iodine, sulphur and carbon are solids.
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Which metals are the best conductors of heat?
- (A) Lead and mercury
- (B) Sodium and potassium
- (C) Iron and lead
- (D) Silver and copper
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Correct answer: (D) Silver and copper
Explanation: Silver and copper are the best conductors of heat, while lead and mercury are poor conductors of heat.
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Sodium metal is kept immersed in what?
- (A) Water
- (B) Alcohol
- (C) Kerosene
- (D) Dilute acid
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Correct answer: (C) Kerosene
Explanation: Sodium reacts with air and water so vigorously that it can catch fire. So it is kept immersed in kerosene.
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Which non-metal catches fire in air and is therefore stored in water?
- (A) Phosphorus
- (B) Sulphur
- (C) Carbon
- (D) Iodine
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Correct answer: (A) Phosphorus
Explanation: Phosphorus is a very reactive non-metal that catches fire in open air. It is stored in water to keep it away from air.
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What is the property of metals that lets them be beaten into thin sheets called?
- (A) Ductility
- (B) Conductivity
- (C) Sonority
- (D) Malleability
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Correct answer: (D) Malleability
Explanation: The property of being beaten into thin sheets is malleability. Being drawn into wires is called ductility.
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What is the property of metals that lets them be drawn into thin wires called?
- (A) Malleability
- (B) Ductility
- (C) Lustre
- (D) Hardness
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Correct answer: (B) Ductility
Explanation: The property of being drawn into wires is ductility. Gold is the most ductile metal: 1 g of gold can be drawn into a wire about 2 km long.
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Which non-metal is a good conductor of electricity?
- (A) Graphite
- (B) Diamond
- (C) Sulphur
- (D) Iodine
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Correct answer: (A) Graphite
Explanation: Graphite, a form (allotrope) of carbon, conducts electricity even though it is a non-metal. Diamond, another allotrope of carbon, does not.
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What is the hardest natural substance?
- (A) Iron
- (B) Graphite
- (C) Diamond
- (D) Platinum
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Correct answer: (C) Diamond
Explanation: Diamond, an allotrope of carbon, is the hardest natural substance. It also has very high melting and boiling points.
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Which metals melt when simply held in the palm of your hand?
- (A) Iron and copper
- (B) Gallium and caesium
- (C) Gold and silver
- (D) Zinc and lead
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Correct answer: (B) Gallium and caesium
Explanation: Gallium and caesium have very low melting points, so the warmth of a palm is enough to melt them.
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Which are amphoteric oxides, reacting with both acids and bases to form salt and water?
- (A) Na₂O and K₂O
- (B) CO₂ and SO₂
- (C) CaO and MgO
- (D) Al₂O₃ and ZnO
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Correct answer: (D) Al₂O₃ and ZnO
Explanation: Aluminium oxide and zinc oxide react with both acids and bases, so they are amphoteric oxides.
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Which metal reacts violently with cold water?
- (A) Iron
- (B) Copper
- (C) Sodium
- (D) Gold
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Correct answer: (C) Sodium
Explanation: 2Na + 2H₂O → 2NaOH + H₂ + heat. So much heat is released that the hydrogen catches fire.
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Which metal does not react with water, not even hot water or steam?
- (A) Copper
- (B) Magnesium
- (C) Iron
- (D) Sodium
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Correct answer: (A) Copper
Explanation: Copper, lead, silver and gold do not react with water. Magnesium reacts with hot water, and iron reacts with steam.
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Which of these metals is the most reactive?
- (A) Zinc
- (B) Iron
- (C) Copper
- (D) Potassium
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Correct answer: (D) Potassium
Explanation: Potassium is at the top of the reactivity series. These four go in the order K > Zn > Fe > Cu.
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What does a sodium atom do when sodium chloride (NaCl) forms?
- (A) It gains one electron to become Na⁻
- (B) It loses one electron to become Na⁺
- (C) It shares electrons with chlorine
- (D) It loses two electrons
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Correct answer: (B) It loses one electron to become Na⁺
Explanation: Sodium gives its one outer electron to chlorine and becomes Na⁺, and chlorine takes it to become Cl⁻. The attraction between these oppositely charged ions forms an ionic bond.
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In which state do ionic compounds conduct electricity?
- (A) When molten or dissolved in water
- (B) Only in the solid state
- (C) In no state
- (D) Only in the gaseous state
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Correct answer: (A) When molten or dissolved in water
Explanation: In the solid state the ions are held in place, so there is no conduction. When molten or dissolved in water, the ions can move, so electricity is conducted.
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What is the process of strongly heating a sulphide ore in excess air to change it into an oxide called?
- (A) Calcination
- (B) Refining
- (C) Roasting
- (D) Galvanisation
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Correct answer: (C) Roasting
Explanation: Heating a sulphide ore in excess air is roasting, for example 2ZnS + 3O₂ → 2ZnO + 2SO₂. Heating a carbonate ore in limited air is called calcination.
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What is the process of strongly heating a carbonate ore in limited air to change it into an oxide called?
- (A) Roasting
- (B) Calcination
- (C) Corrosion
- (D) Reduction
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Correct answer: (B) Calcination
Explanation: Heating a carbonate ore in limited air is calcination, for example ZnCO₃ → ZnO + CO₂.
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Which reaction is used to join railway tracks and cracked machine parts?
- (A) Neutralisation
- (B) Electrolysis
- (C) Calcination
- (D) Thermit reaction
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Correct answer: (D) Thermit reaction
Explanation: Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat. So much heat is released that the iron forms in molten state, which is used to join the tracks.
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In the electrolytic refining of copper, what is the anode made of?
- (A) A thin strip of pure copper
- (B) Graphite
- (C) Impure copper
- (D) Zinc
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Correct answer: (C) Impure copper
Explanation: Impure copper is the anode and a thin strip of pure copper is the cathode. When current flows, pure copper from the anode dissolves and is deposited on the cathode.
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What is coating iron with a layer of zinc to protect it from rusting called?
- (A) Galvanisation
- (B) Roasting
- (C) Calcination
- (D) Alloying
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Correct answer: (A) Galvanisation
Explanation: Coating iron or steel with a thin layer of zinc is called galvanisation. Even if the coating is broken, the zinc still protects the iron from rusting.
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Brass is an alloy of which metals?
- (A) Copper and tin
- (B) Lead and tin
- (C) Iron and nickel
- (D) Copper and zinc
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Correct answer: (D) Copper and zinc
Explanation: Brass is an alloy of copper and zinc. Bronze is made of copper and tin, and solder of lead and tin.
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Solder, used to join electrical wires, is an alloy of which metals?
- (A) Copper and zinc
- (B) Lead and tin
- (C) Iron and chromium
- (D) Gold and silver
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Correct answer: (B) Lead and tin
Explanation: Solder is an alloy of lead and tin. It has a low melting point, so it melts easily to join wires.
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Assertion (A): Aluminium is a reactive metal, yet it is used to make cooking utensils. Reason (R): In air, aluminium gets covered with a thin oxide layer that stops further reaction.
- (A) Both A and R are true, and R is the correct explanation of A.
- (B) Both A and R are true, but R is not the correct explanation of A.
- (C) A is true, but R is false.
- (D) A is false, but R is true.
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Correct answer: (A) Both A and R are true, and R is the correct explanation of A.
Explanation: Both statements are true. The protective oxide layer stops aluminium from corroding further, which is why it is safe for utensils, so R correctly explains A.
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Assertion (A): Most metals do not give hydrogen gas when they react with nitric acid. Reason (R): Nitric acid is a strong oxidising agent that oxidises the hydrogen produced to water.
- (A) Both A and R are true, and R is the correct explanation of A.
- (B) Both A and R are true, but R is not the correct explanation of A.
- (C) A is true, but R is false.
- (D) A is false, but R is true.
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Correct answer: (A) Both A and R are true, and R is the correct explanation of A.
Explanation: HNO₃ is a strong oxidising agent, so the H₂ formed is turned into water and oxides of nitrogen are given off. R correctly explains A. (Mg and Mn do give H₂ with very dilute HNO₃.)