Class 8th Science

  Physical Properties of Metals and Non-metals Physical Properties Metals Non-Metals Conductivity Metals (such as iron or copper) are good conductors of heat and electricity. Non-metals (such as coal or sulphur) are poor conductors of heat and electricity. Graphite is an exception as it is a good conductor of electricity. Ductility Metals (such as aluminium and copper) are ductile, which means that they can be drawn into wires. Non-metals are brittle (break down when struck) and hence, they cannot be drawn into wires. Hardness All metals are hard though there are some exceptions. Sodium and potassium are soft and can be cut with a knife. Most non-metals are soft. Diamonds are exceptions as they are the hardest material found on Earth. However, they are also very brittle and break when struck with a hammer. Lustre Metals (such as gold, silver and copper) are lustrous, which means that they reflect light from their surface and can be polished. Non-metals (such as coal) are generally ...

  Exercise Questions 1. Which of the following can be beaten into thin sheets? (a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen Soln: Answer is a) Zinc Explanation: Here, Zinc is a metal with malleability and ductility whereas Phosphorus, Sulphur and Oxygen are nonmetals which lack malleability and ductility. 2. Which of the following statements is correct? (a) All metals are ductile. (b) All non-metals are ductile. (c) Generally, metals are ductile. (d) Some non-metals are ductile. Soln: Answer is (c) Generally, metals are ductile. Explanation: Ductility is a property where a substance can be drawn into thin wires, Generally, metals are ductile with mercury as the exception. 3. Fill in the blanks. (a) Phosphorus is a very _________non-metal. (b) Metals are _________ conductors of heat and ____________ . (c) Iron is ____________reactive than copper. (d) Metals react with acids to produce ____________ gas. Soln: (a) Phosphorus is a very  reactive  non-metal. (b) Metals ...