Water Exe-3C Short Answer Chemistry Class-9 ICSE Selina Publishers Solutions Chapter-3. Step By Step ICSE Selina Concise Solutions of Chapter-3 Water with All Exercise including MCQs, Very Short Answer Type, Short Answer Type, Long Answer Type, Numerical and Structured/Application Questions Solved . Visit official Website CISCE for detail information about ICSE Board Class-9.
Water Exe-3C Short Answer Chemistry Class-9 ICSE Concise Selina Publishers
| Board | ICSE |
| Publications | Selina Publication |
| Subject | Chemistry |
| Class | 9th |
| Chapter-3 | Water |
| Book Name | Concise |
| Topics | Solution of (Soft and hard Water) Exercise – 3C Short Answer |
| Academic Session | 2023-2024 |
Exercise – 3C Short Answer
Water Class-9 Chemistry Concise Solutions
Page-55
Question 1.
What is the use of solubility of oxygen and carbon dioxide in water?
Answer:
Air dissolved in water is biologically very important.
Oxygen dissolved in water is used by marine life like fish for respiration, and thus, marine life is sustained.
Aquatic plants make use of dissolved carbon dioxide in photosynthesis to prepare food.
Carbon dioxide dissolved in water reacts with calcium carbonate to form calcium bicarbonate.
Marine organisms such as oysters and snails extract calcium carbonate from calcium bicarbonate to build their shells.
Question 2.
Hot saturated Solution of sodium nitrate forms crystals as it cools. Why?
Answer:
Solubility of sodium nitrate decreases with a fall in temperature. Thus, when a hot saturated Solution of sodium nitrate cools, it forms crystals as it separates from the Solution.
Question 3.
What do you understand by?
(a) Soft water
(b) Hard water
(c) Temporary hard water
(d) Permanent hard water
Answer:
(a) Water is said to be soft when the water containing sodium salts easily gives lather with soap.
(b) Water is said to be hard when it does not readily form lather with soap.
(c) Water which contains only hydrogen carbonates of calcium and magnesium is called temporary hard water.
(d) Water containing sulphates and chlorides of magnesium and calcium is called permanent hard water.
Question 4.
What are the causes for?
(a) Temporary hardness
(b) Permanent hardness
Answer:
(a) The presence of hydrogen carbonates of calcium and magnesium makes water temporarily hard.
(b) The presence of sulphates and chlorides of magnesium and calcium makes water permanently hard.
Question 5.
State two ways by which a saturated Solution can be changed to unsaturated Solution.
Answer:
On heating, a saturated Solution becomes unsaturated and more solute can be dissolved in the Solution.
By adding more solvent, a saturated Solution can be made unsaturated.
Question 6.
What is soap? For what is it used?
Answer:
Soap is chemically a sodium salt of stearic acid (an organic acid with the formula C17H35COOH) and has the formula C17H35COONa.
Soap is used for washing purposes.
Question 7.
What is the advantage of a detergent over soap?
Answer:
Detergents are more soluble in water than soap and are unaffected by the hardness of water as their calcium salts are soluble in water.
— : End of Water Exe-3C Short Answer Class-9 ICSE Chemistry Solutions :–
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