Page 124 - Innovator's Science-8

Grasp-Up

Solute: A substance that dissolves in a solvent to form a solu on
Solvent: A substance, usually a liquid, in which a solute dissolves
Solu on: A uniform mixture of a solute and a solvent
Saturated solu on: A solu on that cannot dissolve any more solute at a given temperature
Unsaturated solu on: A solu on that can s ll dissolve more solute at a given temperature
Concentra on: The amount of solute present in a fixed quan ty of solvent
Solubility: The maximum amount of solute that can dissolve in a given quan ty of solvent at a par cular
temperature
Meniscus: The curved surface of a liquid in a measuring container
Density: The amount of mass contained in a unit volume of a substance
Rela ve density: The ra o of the density of a substance to the density of water

Points to Reflect
• A solution is formed when a solute dissolves evenly in a solvent.
• Water is known as a universal solvent because it can dissolve many substances such as sugar and salt.
• The solubility of a solute depends on temperature - it usually increases with an increase in temperature.
• The solubility of gases decreases as the temperature increases.
• Solutions can be unsaturated, saturated, or concentrated depending on how much solute they contain.
• Concentration indicates the strength of a solution and depends on the amount of solute dissolved.
• Objects float or sink in water depending on their density compared to that of water.
• Density is calculated using the formula: Density = Mass/Volume.
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• The SI unit of density is kilogram per cubic metre (kg/m ), while smaller samples are often measured in
grams per cubic centimetre (g/cm ).
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NCERT Textbook Questions (Solved)

Let Us Enhance Our Learning
1. State whether the statements given below are True [T] or False [F]. Correct the false statements.

i. Oxygen gas is more soluble in hot water than in cold water.
ii. A mixture of sand and water is a solu on.
iii. The amount of space occupied by any object is called its mass.
iv. An unsaturated solu on has more solute dissolved than a saturated solu on.
v. The mixture of different gases in the atmosphere is also a solu on.
Ans. I. False. Oxygen gas is more soluble in cold water rather than hot water.
ii. False, A mixture of sand and water is a non-uniform mixture, not a solu on.
iii. False, The amount of space occupied by any object is called its volume.
iv. False, A saturated solu on has more (or equal) solute dissolved than an unsaturated solu on. An
unsaturated solu on can s ll dissolve more solute.
v. True

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Science-8