MCQ (Solution) - The Amazing World of Solutes, Solvents, and Solutions | Science Curiosity Class 8 - New NCERT PDF Download

Answer: Option C
Solution:

• A uniform mixture like sugar in water is a solution; the substance present in smaller amount that dissolves (sugar) is the solute, while the medium (water) is the solvent.
• Even when sugar is large in amount (as in chashni), water remains the solvent by definition in a solid–liquid solution.
• Why others are incorrect: A reverses roles; B and D misuse solution terminology.

Answer: Option B
Solution:

• Air is a uniform mixture of gases; the major component (nitrogen) is treated as the solvent and minor components (oxygen, argon, CO₂, etc.) as solutes.
• Why others are incorrect: A implies chemical bonding (not true here); C refers to pollutants not defining uniformity; D misclassifies air.

Answer: Option C
Solution:

• A saturated solution holds the maximum solute at that temperature; additional solute remains undissolved at the bottom.
• An unsaturated solution can still dissolve more solute at that temperature.
• Why others are incorrect: A relates to concentration level; B is the opposite case; D is a different dispersion type.

Answer: Option B
Solution:

• For most solids in liquids, solubility increases with temperature; heating converts a saturated solution at lower temperature into an unsaturated one at higher temperature.
• Why others are incorrect: A reduces solubility; C does not increase the solubility limit; D is irrelevant and insoluble.

Answer: Option A
Solution:

• Concentration refers to amount of solute per fixed amount of solution/solvent; “concentrated” means higher proportion than “dilute.”
• These are relative terms depending on the comparison basis.
• Why others are incorrect: B reverses; C ignores differences; D contradicts their relative nature.

Answer: Option B
Solution:

• Gas solubility in liquids typically decreases with higher temperature and increases as temperature falls; cold water holds more dissolved oxygen, sustaining aquatic life.
• Why others are incorrect: A lowers gas solubility; C and D don’t target the correct trend.

Answer: Option C
Solution:

• Floating indicates oil’s density is lower than water’s; oil is also immiscible, so layers form with oil on top.
• Why others are incorrect: A predicts sinking; B does not occur; D misassigns solvent roles.

Answer: Option B
Solution:

• Density is mass per unit volume; SI unit is kg/m³; for liquids and small samples, g/mL or g/cm³ is common (1 mL = 1 cm³).
• Why others are incorrect: A inverts; C multiplies; D uses wrong denominator.

Answer: Option A
Solution:

A tall, narrow column produces more noticeable level changes per small volume, enabling finer graduations and accurate meniscus reading at eye level.

Answer: Option B
Solution:

• For most colourless liquids (like water), read the bottom of the meniscus with eyes level to avoid parallax error; for opaque/coloured liquids, read the top edge.
• Why others are incorrect: A inverts the rule; C causes parallax error; D is arbitrary.

Answer: Option D
Solution:

• Displacement gives volume = 55−50 = 5 mL = 5 cm³; density = 16.400 g / 5 cm³ = 3.28 g/cm³.
• Since water is ~1 g/cm³, this object is denser than water and would sink.

Answer: Option B
Solution:

• As temperature rises, particles move apart; volume increases, mass constant ⇒ density (mass/volume) decreases; hot air rises for this reason.
• Water has special behavior near 4°C, but the general trend holds.
• Why others are incorrect: A and D contradict typical behavior; C overlooks thermal expansion.

Answer: Option B
Solution:

• Water’s structure expands on freezing, decreasing density; water is densest near 4°C, so ice (0°C) is less dense and floats, insulating water below.
• Why others are incorrect: A gets trend wrong; C mass doesn’t vanish; D is physically wrong.

Answer: Option A
Solution:

• Gases are compressible; higher pressure reduces volume at constant mass (and often constant temperature), thereby increasing density.
• Why others are incorrect: B expands gas; C expands volume at constant pressure; D lowers density.

Answer: Option A
Solution:

• A: 200/40 = 5.0 g/cm³; B: 240/60 = 4.0 g/cm³; both densities exceed ~1 g/cm³, so both would sink; A is denser than B.
• Why others are incorrect: B reverses; C miscalculates; D miscomputes density and floating behavior.