Ans)

1. We can use the battery, bulbs, wires and a switch to set up a circuit with the sample. If the sample conducts electricity then it is a metal otherwise it is a non-metal. We can also beat the sample with a hammer. If it can be beaten into thin sheets, i.e. it is malleable, then it is a metal otherwise it is a non-metal.
2. ) In the above tests, no chemical reactions are involved and they are based on the physical properties of metals and non-metals. Hence, they are useful in distinguishing between metals and non-metals.

Ans) Two ways to prevent the rusting of iron are-

1. Oiling, greasing or painting – By applying oil, grease or paint, the surface becomes water proof and the moisture and oxygen present in the air cannot come into direct contact with iron. Hence, rusting is prevented.
2. Galvanisation – It is a method of protecting iron from rusting by coating an iron article with a thin layer of zinc. It prevents the iron to come in contact with oxygen and moisture. The galvanised article is protected against rusting even if the zinc coating is broken.

1. Platinum, gold and silver are used to make jewellery.
2. Sodium, potassium and lithium are stored under oil.
3. Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
4. Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

Ans)

1. Platinum, gold and silver are used to make jewellery because they are lustrous. Also, they are very less reactive and do not corrode easily.
2. Sodium, potassium and lithium are very reactive metals. They react vigorously with air as well as water. Therefore, they are kept immersed in kerosene oil in order to prevent their contact with air and moisture.
3. Aluminium is a highly reactive metal but it is resistant to corrosion. This is because aluminium reacts with oxygen present in air to form a thin layer of aluminium oxide (Al₂O₃). The reaction is 4AI + 30₂ → 2Al₂O₃.. This oxide layer is very stable and prevents further reaction of alumnium with oxygen. Also, aluminium is light in weight and a good conductor of heat. That is why it is used to make cooking utensils.
4. Carbonate and sulphide ores are usually converted into oxides during the process of extraction because metals can be easily extracted from their oxides rather than from their carbonates and sulphides.

Ans) Differences between Metals and Non-metals are:

Metals	Non-Metals
Metals are electropositive.	Non-metals are electronegative.
Metals displace hydrogen from dilute.	They cannot replace hydrogen from dilute acids.
Oxides of metals are basic in nature.	Oxides of non-metals are acidic in nature.
Metals form chlorides which are electrovalent or ionic compounds.	Non-metals form chlorides which are covalent compounds.
Metals react with water to form oxides and hydroxides. Some metals react with cold water, some with hot water, and some with steam.	They do not react with water.

Ans) The solution he had used was Aqua regia. Aqua regia is a Latin word which means ‘Royal water’. It is a freshly prepared mixture of conc. hydrochloric acid and conc. nitric acid in the ratio 3: 1. It is capable of dissolving gold and platinum.

Ans) Physical properties of metals are:

1. Metals generally are good conductors of heat and electricity.
2. Metals generally are melleable.
3. Metals generally are ductile.
4. In general metals are hard.
5. In general metals are sonorous.