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Hydrogen

Short Answer Type

121. Write chemical reactions to show amphoteric nature of water.

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122.

Give two chemical reactions in which water acts as a reducing agent.

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123.

Give two points to distinguish between fresh tap water and distilled water.

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124.

Water has some air dissolved in it. What is its significance?

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Long Answer Type

125.

What properties of water make it useful as a solvent? What type of compounds can it: (i) dissolve and (ii) hydrolyse?

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Short Answer Type

126.

Why is water an excellent solvent for ionic and polar compounds?

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127. What do you understand by the term ‘auto-protolysis’ of water? What is its significance?

Auto-protolysis of water. Auto-protolysis of water means its self-ionisation. Self-ionisation of water can be represented as:

The significance of auto-protolysis. water shows its amphoteric nature due to autoprotolysis i.e. water reacts with both acids and bases.

Water acting as an acid:

Water acting as a base:

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Long Answer Type

128. Describe the usefulness of water in the biosphere and biological system.

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Short Answer Type

129.

What are the ways in which water molecules are bound to an anhydrous salt to form a hydrate?

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130.

How many hydrogen - bonded water molecule(s) are associated in CuSO₄.5H₂O?

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