Nature of Matter: Elements, Compounds, and Mixtures MCQs (Class 8 Science, NCERT)
110 practice questions on Nature of Matter: Elements, Compounds, and Mixtures, a chapter in the NCERT Class 8 Science textbook, with a dedicated set on Mixtures. Every question includes a written explanation. Pick a topic below, or try the samples first.
Which pair gives one metal and one non-metal in that order?
AOxygen and sulphur
BCopper and oxygen
CCopper and iron
DWater and common salt
Show answer and explanation
Correct answer: B - Copper and oxygen
Copper is a metal and oxygen is a non-metal, so this pair fits. Copper and iron are both metals, while oxygen and sulphur are both non-metals. Water and salt are compounds, not elements, so they cannot be classed as metal and non-metal.
Q2
medium
A town decides to repair its old metal water pipes instead of replacing all of them with new ones. How does this help?
AIt makes no difference at all to mineral resources
BNew minerals are created beneath the town
CLess fresh metal is needed, so mineral resources are saved
DThe old pipes are turned back into ore
Show answer and explanation
Correct answer: C - Less fresh metal is needed, so mineral resources are saved
Repairing keeps the existing metal in use, so less ore must be mined to make replacements. Repair work does not create minerals underground, and a pipe cannot turn back into ore. Since less new metal is needed, the effect on resources is real, not zero.
Q3
hard
Assertion (A): A bottle labelled 'pure fruit juice' need not contain a pure substance in the scientific sense. Reason (R): In science a pure substance may contain any number of different substances, provided none of them is harmful.
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: C - A is true, but R is false
The assertion is true, since juice holds water, sugars and acids together and is a mixture. The reason is false: a scientifically pure substance holds one substance only, whether or not the others are harmful. Only the assertion stands.
Q4
medium
Sea water contains several salts dissolved in water. Sea water is best described as
Aa compound
Ban element
Ca substance with a fixed composition
Da mixture
Show answer and explanation
Correct answer: D - a mixture
Dissolved salts sit in the water without combining chemically with it, so sea water is a mixture. A compound would have its parts chemically joined, and an element would contain only one kind of particle. Sea water from different places contains different amounts of salt, so its composition is not fixed.
Q5
easy
The iron used for making railway tracks is obtained from
Aan ore dug out of the ground
Bthe leaves of tall trees
Cthe foam on sea waves
Dthe air around us
Show answer and explanation
Correct answer: A - an ore dug out of the ground
Iron is taken out of iron ore mined from the Earth. Trees give wood and fibres but no iron, sea foam is mostly air and water, and the air contains gases, not metals.
Q6
easy
Which of these is a mineral obtained from the Earth?
ARock salt
BA plastic bucket
CA cotton cloth
DA sheet of paper
Show answer and explanation
Correct answer: A - Rock salt
Rock salt is dug out of the ground, where it formed naturally, so it is a mineral. Plastic is manufactured, while paper and cotton cloth are made from plants, so none of these three is a naturally occurring mineral.
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