3. Name the following: (a) A metal, which is preserved in kerosene. (b) A lustrous coloured non-metal. (c) A metal, which can melt while kept on palm. (d) A metal, which is a poor conductor of heat.
Answers
Name the following:
(a) A metal, which is preserved in kerosene.
Answer:- Sodium is stored in kerosene as it is a very highly reactive metal. If it is kept in open air, it easily reacts with the oxygen and catches fire. Since kerosene is a mixture of hydrocarbons, it won't react with it.
(b) A lustrous coloured non-metal.
Answer:- Lustrous coloured non-metal - IODINE and DIAMOND. They have a slight metallic lustre. The presence of lustre in diamond is not due to free electron but due to its high refractive index.
(c) A metal, which can melt while kept on palm.
Answer:- Metal which can melt while kept on palm are - GALLIUM & CAESIUM. They exhibit very low melting point. The melting point of gallium is 29.8°C and the melting point of caesium is 28.5°C.
(d) A metal, which is a poor conductor of heat.
Answer:- Metal which are poor conductor of heat are - MERCURY & LEAD. Mercury is the poorest conductor of heat.
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Answer:
(a) Sodium
(b) Gold
(c) Galium, Cassium
(d) Lead