Pure Substance and Mixture Quiz
Questions: 16 · 10 minutes
1. Two colorless liquids are heated separately at the same constant pressure. Liquid A boils at one steady temperature, while Liquid B boils across a range. Which conclusion is best supported?
Both liquids must be elements.
Liquid A is more consistent with a pure substance than Liquid B.
Liquid B must be a pure compound.
Neither liquid can contain molecules.
2. A student tries to separate dissolved sugar from water by pouring the solution through ordinary filter paper. Why does this method fail?
Sugar chemically becomes water when it dissolves.
Filter paper can separate only mixtures of two liquids.
The solution is a pure substance and therefore cannot be separated.
Dissolved sugar particles pass through the filter along with the water.
3. A beaker contains salt completely dissolved in water. Which method can recover the salt from the solution?
Filtration through ordinary filter paper
Allowing the salt to settle and decanting the water
Using a magnet
Evaporating the water
4. A black ink separates into several colored bands as a solvent moves across chromatography paper. What does this show?
The solvent chemically converts the ink into new elements.
The ink is an element that changes color during movement.
The ink contains components with different attractions to the paper and solvent.
Each band is produced because the paper melts part of the ink.
5. Every pure sample of carbon dioxide contains carbon and oxygen in the same definite proportion. What does this support?
Carbon dioxide is a heterogeneous mixture.
Carbon dioxide is an element because it has one formula.
Carbon dioxide can be separated into its elements by simple filtration.
Carbon dioxide is a compound with a fixed composition.
6. A clear sports drink looks uniform but contains water, sugars, flavorings, and dissolved salts. Why is it still a mixture?
All clear liquids are mixtures.
Its components are physically combined and their proportions can vary.
A uniform appearance means it contains only one chemical element.
Dissolving substances always creates a new pure compound.
7. Which statement distinguishes a compound from a mixture?
A compound always contains only one type of atom.
A compound can always be separated by filtration.
A compound can be broken into simpler substances only through chemical changes.
A compound's components retain all their original physical properties.
8. Brass is an alloy of copper and zinc that is uniform throughout at the observable scale. How is it usually classified?
A homogeneous mixture
A pure compound with a fixed formula
A heterogeneous mixture
A pure element
9. Granite commonly contains visibly different mineral grains. What type of material is it?
A pure element
A heterogeneous mixture
A homogeneous mixture
A pure compound
10. Which description correctly classifies oxygen gas made only of O₂ molecules?
A compound, because each particle contains two atoms
A mixture, because the atoms can move independently
A pure element, because it contains only oxygen atoms
A heterogeneous substance, because oxygen is molecular
11. After soil is stirred into water, solid particles remain visible and later settle. How should the sample be classified?
A pure compound, because the soil contacts the water
A pure substance, because settling produces layers
A homogeneous mixture, because both materials are in one container
A heterogeneous mixture, because its composition is not uniform throughout
12. A student mixes iron filings with sulfur powder without heating them. How should the result be classified?
A mixture, because the substances retain their properties and can be separated physically
A compound, because two elements are present
An element, because both components are solids
A pure substance, because the mixture looks uniform from a distance
13. A sealed sample contains only distilled water. Which classification is most accurate?
A homogeneous mixture, because hydrogen and oxygen are evenly distributed
An element, because the sample contains one kind of molecule
A pure compound, because it consists of water molecules in a fixed ratio
A heterogeneous mixture, because liquid water contains moving particles
14. Oil and water form two separate liquid layers. Which method is most suitable for separating them in a laboratory?
Using a separating funnel to drain the layers individually
Passing the liquids through chromatography paper
Using a magnet to attract the denser layer
Filtering the mixture to trap the water as a solid
15. Which statement best defines a pure substance?
It contains only one visible phase.
It has a fixed composition and characteristic properties.
It cannot undergo any chemical change.
It consists only of individual atoms.
16. What does the fixed composition of a compound mean?
Its constituent elements are chemically combined in a definite ratio.
Its ingredients can be combined in any proportion.
Its particles must all be single atoms.
Its composition changes when the sample size changes.