Question

Answer the following

1.Name a metal and a non-metal existing in liquid state at room temperature.

2.Which one of Cu ,Ag and Au is most malleable?

3.Which one of Fe, Ag and Pb is best conductor of heat?

4.Which one of Cu ,Fe and Ag offers great resistance to the flow of electric current?

5.Which one of Na, Cu and Zn can be cut easily with a knife?

6. Which one of Cu, Mg and Na is stored in kerosene ? Why ?

7.Copper is used in electrical appliances. Give two reasons based on its physical
properties.

8.In solid state NaCl does not conduct electricity but in molten state and inaqueous
solution it conducts electricity. Give separate reasons for each observation.

9.What is an alloy?How do the properties of an alloy differ from its constituents ? Give
one example.

10.Name the metals present in magnalium?​

Answer 1

Explanation:

1. metal: mercury, non metal: bromine
2. Cu
3. Ag
4. Fe
5. Na
6. Na. It is kept in kerosene to prevent it from coming in contact with oxygen and moisture. If this happens, it will react with the moisture present in air and form sodium hydroxide which is a highly exothermic reaction.
7. Thermal resistance and high conductivity
8. Sodium chloride is an ionic compound having sodium and chloride ions in its structure. Ionic compounds do not conduct electricity in solid state but they conduct electricity in aqueous solution and in molten state. Hence this property is shown by sodium chloride.
9. An alloy is a homogeneous mixture of two or more metals or non metals.Alloys are stronger and harder than the constituent metals. Alloys are more resistant to corrosion. Alloys have lower melting point than the constituent metals. Alloys have lower electrical conductivity than pure metals. Example: brass, bronze
10. Magnesium and aluminium.

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