(b) Iodine is lustrous coloured non-metal.
(c) Gallium. ‘
1.Metal which are preserved in kerosene - SODIUM, LITHIUM AND POTASSIUM. They are very reactive metals in order to prevent them to react with oxygen it is kept immersed in kerosene oil. The reaction of these metals with air is so vigorous that they catch fire automatically.
2. 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.
3. 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.
4. Metal which are poor conductor of heat are - MERCURY & LEAD. Mercury is the poorest conductor of heat.
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