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Materials: Metals and Non-metals
Give reasons for the following.
(a) Aluminium foils are used to wrap food items.
(b) Immersion rods for heating liquids are made up of metallic substances.
(c) Copper cannot displace zinc from its salt solution.
(d) Sodium and potassium are stored in kerosene.
(a) Aluminum is a soft metal that can be easily beaten into thin sheets. It has a smooth shiny surface that reflects the heat coming from food. Hence, it is used to make a food wrapping sheet as it keeps the food warm for a longer time.
(b) Immersion rods are made from metals because metals are good conductors of heat and electricity. They get hot very soon on passage of electric current and warm the water.
(c) Copper is a less reactive metal than Zinc. Hence, it cannot displace zinc from its salt solution.
(d) Metals like sodium and potassium react vigorously with oxygen and catch fire if kept in open. Hence, they are kept in kerosene oil to prevent burning.
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