(1)

Sodium is a very reactive metal. It reacts so vigorously that it catches fire if kept in the open. Therefore, to prevent the accidental fires, it is kept immersed in kerosene oil. Thus, both assertion and reason are correct and reason is the correct explanation of the assertion.

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Platinum, gold, and silver are used to make jewellery because they are very lustrous. Also, they are very less reactive and do not corrode easily. Thus, both assertion and reason are correct and reason is the correct explanation of the assertion.

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Copper is not reactive to any form of water, such as steam, neither cold water nor hot water. Hence, the copper is used to make the hot water tanks as it does not react with the water. On the other hand, due to the presence of iron in the steel, Steel is not used to make hot water tanks.

(2)

An alloy is combination of a metal and a non-metal. So it has partial characteristics of metal and non-metal. In an alloy the ions are randomly arranged. It does not have a specific arrangement of ions. Hence, the flow of electrons in this is more. This feature of alloy leads to increase in resistivity due to free crystal lattice. Thus, both assertion and reason are correct but reason is not the correct explanation of the assertion.

(2)

Aluminium is a highly reactive metal but it is resistant to corrosion. The reason for this is that aluminium reacts with oxygen present in air to form a thin layer of aluminium oxide. This oxide layer is very stable and prevents further reaction of aluminium with oxygen. It is light in weight and a good conductor of heat. Therefore, used to make utensils for cooking. Thus, both assertion and reason are correct, but reason is not the correct explanation of the assertion.

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Tungsten is used for filament of electric bulb because it has high melting point and high resistance. Thus, both assertion and reason are correct and reason is the correct explanation of the assertion.

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School bells are made up of metals because metals are sonorous, i.e., when bells are hit, they vibrate and produce sound. Thus, both assertion and reason are correct and reason is the correct explanation of the assertion.

(2)

Ionic compounds are made up of positive and negative ions. There is a strong electrostatic force of attraction between them. A lot of heat energy is required to break this force of attraction and to melt or boil the ionic compound. As a result, ionic compounds have high melting points. Thus the assertion and reason are correct, but reason is not the correct explanation of the assertion.

(1)

Reactivity Series is an arrangement of element based on their reactivity in the increasing or the decreasing order and this series is used to separate elements based on their reactivity. Thus both assertion and reason are correct and reason is the correct explanation of the assertion.

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