Class 8 Science: The Amazing World of Solutes, Solvents, and Solutions MCQs (NCERT)
110 practice questions on The Amazing World of Solutes, Solvents, and Solutions, a chapter in the NCERT Class 8 Science textbook, organised into 3 topics. Every question includes a written explanation. Pick a topic below, or try the samples first.
A block has a mass of $60\ \text{g}$ and a volume of $30\ \text{cm}^3$. Its density is
A$30\ \text{g/cm}^3$
B$1800\ \text{g/cm}^3$
C$0.5\ \text{g/cm}^3$
D$2\ \text{g/cm}^3$
Show answer and explanation
Correct answer: D - $2\ \text{g/cm}^3$
Density is mass divided by volume, so it is $60 \div 30 = 2\ \text{g/cm}^3$. Dividing the volume by the mass gives $0.5$, which is the common reversal slip. The value $30$ is just the volume copied down, and $1800$ comes from multiplying instead of dividing.
Q2
hard
Assertion (A): Sugar can be separated from a sugar solution by pouring the solution through filter paper. Reason (R): Dissolved sugar particles are much smaller than the pores of filter paper.
ABoth A and R are true, and R is the correct explanation of A
BBoth A and R are true, but R is not the correct explanation of A
CA is true, but R is false
DA is false, but R is true
Show answer and explanation
Correct answer: D - A is false, but R is true
A is false, because the sugar passes straight through the paper along with the water and nothing is left behind. R is true, and it is exactly the reason why filtration fails here. A false assertion paired with a true reason gives the fourth choice.
Q3
medium
Equal volumes of milk and honey are taken in two identical cups and weighed. The cup of honey is found to be heavier. It follows that
Athe two have equal densities
Bmilk is denser than honey
Choney is denser than milk
Dhoney occupies a larger volume than milk
Show answer and explanation
Correct answer: C - honey is denser than milk
For equal volumes, the heavier sample has more mass in the same space, so honey is denser. Saying milk is denser reverses this, and equal densities contradict the weighing. The volumes were made equal at the start, so honey cannot occupy more space.
Q4
easy
Sugar is stirred into a glass of water until it has all dissolved. A sip taken from the top and a sip taken from near the bottom will taste
Asweeter at the bottom, where the sugar settles
Bsweeter at the top
Cdifferent each time the glass is used, depending on how it was stirred
Dequally sweet, because a solution is uniform throughout
Show answer and explanation
Correct answer: D - equally sweet, because a solution is uniform throughout
In a solution the solute spreads evenly, so every part has the same composition and the same sweetness. Dissolved sugar does not settle to the bottom, and nothing pushes it upwards either. Once all the sugar has dissolved, a uniform mixture gives the same taste every time, whatever the stirring.
Q5
hard
Sea water is first passed through a cloth to remove sand and bits of weed, and then left in wide shallow pans in the Sun. After some days workers collect a white solid from the pans. Which statement about this solid is correct?
AIt is the sand that slipped through the cloth
BIt came off the walls and floor of the pan
CIt was created by sunlight acting on the water, which turns part of the water into a white powder
DIt was dissolved in the sea water and stayed behind when the water evaporated
Show answer and explanation
Correct answer: D - It was dissolved in the sea water and stayed behind when the water evaporated
The salt was already dissolved in the sea water, and evaporation removes only the water, so the salt is left in the pan. Sunlight supplies heat but cannot create a new substance. The pans give the same yield whatever they are lined with, and the sand was removed before the water reached the pans.
Q6
medium
Consider these statements. Statement I: Powdering a solid raises the amount of it that a fixed quantity of water can hold. Statement II: Powdering a solid raises the rate at which it dissolves.
ABoth statements are wrong
BOnly Statement II is correct
CBoth statements are correct
DOnly Statement I is correct
Show answer and explanation
Correct answer: B - Only Statement II is correct
Powdering exposes more surface, so the solid dissolves faster and Statement II is correct. The greatest amount a solvent can hold depends on the substances and the temperature, not on the size of the pieces, so Statement I is wrong.
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