Chemistry
Assertion (A): Water is a universal solvent.
Reason (R): Water dissolves all substances except noble metals and glass.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Water
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Answer
A is true but R is false.
Explanation — Water dissolves many substances, forming aqueous solutions. Not only solids but gases and other liquids can also dissolve in water to a large extent. For this reason, water is called a universal solvent. Hence the assertion (A) is true.
It is true that nobel metals and glass does not dissolve in water but all compounds do not dissolve in water; for instance, many nonpolar substances, such as oils, do not dissolve in water. Hence reason (R) is false.
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Related Questions
Some salts while crystallising out from their solutions, combine with a definite quantity of water. Some of these salts lose this water on exposure to dry air. Certain water soluble substances, when exposed to atmosphere at ordinary temperatures, absorb moisture from atmospheric air forming a saturated solution.
(a) State the term used for a 'definite quantity of water' combined with a salt.
(b) What type of salts lose their water molecules ? Give two examples.
(c) Table salt forms a solution on exposure to air during rainy season. Explain.
(d) How can pure sodium chloride be obtained from the above table salt solution in (c) ?
The following figure shows the solubility curves of NaCl, KNO3 and hydrated calcium sulphate.
(a) Identify and label the curves with the salt it represents.
(b) State the factors on which the solubility depends.
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(ii) Exothermic process?
Assertion (A): A saturated solution becomes unsaturated on heating.
Reason (R): More amount of solute can dissolve in a solvent upon heating.
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- Both A and R are true but R is not the correct explanation of A.
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- A is false but R is true.
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Reason (R): Washing soda is a hygroscopic substance.
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- A is true but R is false.
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