CBSE Class 8 Science Materials : Metals and Non-Metals Worksheets with Answers - Chapter 4 - PDF
FAQs on CBSE Class 8 Science Materials : Metals and Non-Metals Worksheets
1. Why is sodium stored in kerosene?
Owing to sodium’s chemical properties, the element is a very reactive metal. It reacts vigorously with both oxygen and water. An exothermic reaction takes place in which sufficient heat is generated to start a fire. Thus, to prevent sodium from being exposed to moisture or air, it is stored in kerosene. In complete contrast to this, most non-metals do not react with water despite being very reactive in air. Such non-metals are thereby stored in water. Phosphorus is a non-metal that is readily stored in water to prevent contact with air.
2. What does it mean if a metal is malleable?
Some metals exhibit the property of malleability. This means that upon beating, these metals can be turned into thin sheets. A very common example in everyday life can be seen when silver foil is used for decorating sweets. Silver is beaten down into thin sheets to obtain that shape. This is also how aluminium foil is produced. This foil can be used for wrapping food as it does not react adversely with moisture or air. Only precious metals like gold, silver, platinum alongside iron and aluminium are malleable. Non-metals also do not show this property.
3. Does copper rust?
You must have observed a greenish deposit on the surface of copper vessels if they are left exposed to air or moisture for too long. This dull green coating is made of two chemicals. It is a mixture of copper hydroxide and copper carbonate. In the presence of carbon dioxide and oxygen, the copper metal reacts with water to form these substances that end up imparting the green colour we have noticed. The chemical equation for this reaction has also been provided in the NCERT Class 8 Science textbook.
4. What are some uses of non-metals?
Less than 20 elements in the periodic table are non-metals but they still play a crucial role in sustaining human life. Life-saving gases like oxygen are non-metallic. Nitrogen, phosphorus, and carbon compounds are non-metallic and are used as fertilizers that help in the production of healthy crops. Iodine is another non-metal that is used as an antiseptic for mild cuts and bruises. Chlorine is used in the water purification process. This proves that non-metals are of extreme importance and serve several uses.
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