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7th Grade Science Unit 5

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  • What is bronze made from?
    Copper and tin.
  • What does a toxic symbol (☠) mean?
    The substance can poison you.
  • Why is helium used in balloons?
    It is lighter than air.
  • Why is gold used for jewellery?
    It is shiny, beautiful, and expensive.
  • What is duralumin?
    An aluminium alloy used in airplanes.
  • What does 'ductile' mean?
    A material that can be stretched into wires.
  • Why are alkalis dangerous to the eyes?
    They can cause serious burns or blindness.
  • Which metal is liquid at room temperature?
    Mercury.
  • What gas is used in hospitals to help with breathing?
    Oxygen.
  • How can you separate food dye from water?
    Using a condenser to collect pure water.
  • What does 'malleable' mean?
    A material that can be hammered or bent into shape.
  • What hazard symbol represents something flammable?
    🔥 (Flame).
  • Why do non-metals look dull?
    They do not reflect light well.
  • Why are metals good electrical conductors?
    They allow electric current to flow through them.
  • What is sulfur used for?
    It is added to rubber to make it harder.
  • Name two metals that are magnetic.
    Iron and nickel.
  • What does 'brittle' mean?
    A material that shatters easily when dropped.
  • Why is iron used for bridges?
    It is strong and can hold large weights without breaking.
  • What is an insulator?
    A material that does not conduct electricity.
  • What happens when saltwater is heated in an evaporating dish?
    The water evaporates, leaving salt behind.
  • What are Olympic medals made from?
    Alloys of gold, silver, and bronze.
  • What does 'corrosive' mean?
    A substance that can burn or damage living tissue.
  • What are metals?
    Metals are useful materials that objects are made from.
  • Name a food that contains acid.
    Lemons, limes, or oranges.
  • Name one similarity between brass and bronze.
    Both contain copper.
  • Why are coins made from alloys?
    Pure metals are too soft for everyday use.
  • What happens when an acid and an alkali mix?
    They neutralize each other.
  • Name three properties of metals.
    Strength, malleability, and ductility.
  • Give an example of a ductile metal.
    Copper.
  • What is an alloy?
    A mixture of metals.
  • Why is filtration used to separate sand from saltwater?
    Sand does not dissolve, so it remains in the filter.
  • Why is stainless steel useful for cutlery?
    It does not rust.
  • Why should you not stir the mixture while filtering?
    It may push solid particles through the filter.
  • What is shape memory alloy used for?
    Glasses frames.
  • Why is pure gold not used for jewellery?
    It is too soft.
  • How can you test if a substance is an acid or an alkali?
    Use an indicator like red cabbage juice.
  • Why are titanium alloys used in artificial joints?
    They are strong, durable, and resistant to corrosion.
  • What should you do if you spill acid on your skin?
    Wash the area with plenty of water.
  • Why are alloys stronger than pure metals?
    Different-sized atoms prevent the layers from sliding.
  • Why is steel harder than iron?
    It contains carbon, which strengthens the metal.
  • What happens to the surface of most metals over time?
    It becomes dull.
  • What safety equipment should be worn when handling acids?
    Safety glasses and gloves.
  • Why is chlorine added to swimming pools?
    To kill bacteria.
  • Why are non-metals used for pan handles?
    They do not conduct heat well.
  • What does 'sonorous' mean?
    A material that makes a ringing sound when hit.
  • Why does brass have a range of melting points?
    The ratio of copper to zinc varies.
  • Name five non-metals.
    Oxygen, carbon, chlorine, sulfur, and silicon.
  • Why should you stand up while working with chemicals?
    To avoid spills onto your body.
  • Why do metals feel cold when touched?
    They are good conductors of heat and take heat away from your hand.
  • Name a strong alkali.
    Sodium hydroxide.
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