Important questions based on NCERT syllabus for Chapter 3 - Metals and Non-metals:
Question-1: Explain physical state and hardness of metals?
Solution: 1. Physical state of metals: Most of the metals are solid under normal conditions of temperature and pressure (Except mercury which exist in liquid state at room temperature) For example: Iron, Copper, Aluminium, Zinc, Sodium are solid at room temperature.
2. Hardness of metals: Most of the metals are hard, but all metals are not equally hard. The hardness of metals varies from metal to metal. For example : Iron, Copper, Aluminium, Sodium and Potassium.
Question-2: Write the uses of aluminium, copper and steel.
Solution: 1. Aluminium is used to prepare utensils and house hold equipments like vacuum cleaner. Aluminium is extensively used in making bodies of rail, cars, automobiles, trucks and aircraft. Aluminium wires are widely used in electrical work. Aluminium foil is used to wrap chocolate cigarette and medicines and to seal milk bottles.
2. Major use of copper is in making electrical wires. Copper is also used in making utensils, steam pipes, coin and in electroplating.
3. Steel is an alloy of iron which is used for making parts of machines, as building material and in the construction of fridges. As a matter of fact steel is said to be the back bone of industry. Gold and silver called noble metals (or coinage metals) are used in jewellery.
Question-3: In nature, aluminium is found in the form of compounds while gold is found in free state. Give reason.
Solution: 1. This is because of the relative positions of the metals in the activity series. Aluminium is a reactive metal as it is placed above hydrogen in the activity series.
2. It reacts vigorously and exists in combined form. Gold is placed much below hydrogen in the series. It is very less reactive and does not form compoounds easily, hence it occurs in the free state.