Properties of Elements

 

2) Sodium Is Metal, but Unlike Other Metals, It Starts Burning When It Comes in Contact With Water. Why?

• Sodium is a highly reactive metal.
• As soon as it comes in contact with water, it produces a large amount of heat, making it catch fire.

 

3) What Is the Meaning of Lustre? How Can You Distinguish Between Materials Based on Their Lustre?

• The shiny appearance observed for some materials is called lustre.
• Materials are broadly classified into metals and non-metals based on their lustre.
• For instance, gold and silver are metals, whereas rubber and wood are non-metals.

 

4) Name Any Two Elements Which Are Used for Making Jewellery. State the Reason for the Same.

Gold and silver are used to make jewellery. These elements are less reactive and do not corrode easily; hence, they can be shaped to form jewellery.

 

5) Do elements play any role in our bodies? If yes, enlist them.

Yes, elements like potassium, calcium, iodine and iron play a vital role in our bodies. Their functions are as follows—

• Iron is required for the formation of haemoglobin, which is an essential pigment in our body.
• Calcium and phosphorus are required for healthy and strong bones.
• Iodine is required for the proper functioning of the thyroid gland which regulates the growth and development of our body.

 

6) An Iron Bell Creates a Ringing Sound When It Hits Any Surface. Can You State a Reason Behind It?

Iron is a metal. Metals are sonorous, i.e., they produce a ringing sound when they hit any surface.