Compounds and Mixtures Quiz
Questions: 16 · 10 minutes
1. A student wants to collect pure water from a salt solution while leaving the salt behind. Which method is most suitable?
Simple distillation, because water vaporizes and is then condensed separately.
Filtration, because dissolved salt remains on the filter paper.
Chromatography, because water travels farther than salt.
Magnetic separation, because salt is attracted to a magnet.
2. A container holds two liquid layers: oil on top and water below. Which apparatus is best suited to separate and collect both liquids?
A filter funnel, because one liquid will remain as residue.
A condenser, because both liquids must first be boiled.
Chromatography paper, because each liquid will form a different spot.
A separating funnel, because the immiscible layers can be drained separately.
3. Sodium is a reactive metal, and chlorine is a poisonous gas. Sodium chloride is an edible solid when used appropriately. What does this illustrate?
A mixture always has properties unrelated to those of its components.
Elements retain all their original properties when they form a compound.
A compound can have properties very different from those of its constituent elements.
Compounds contain elements in proportions that can change freely.
4. A sample of muddy water contains insoluble soil particles suspended in water. Which method would most directly remove those particles?
Filtration
Simple distillation
Paper chromatography
Crystallization
5. Brass is made by combining copper and zinc, and its proportions can be adjusted to alter its properties. How should brass be classified?
As an element, because it has metallic properties throughout.
As a compound, because copper and zinc form a fixed chemical formula.
As a homogeneous mixture, because its components are uniformly distributed but can vary in proportion.
As a pure substance, because it appears uniform to the eye.
6. Why is clean, dry air classified as a mixture rather than a compound?
Its components are all gases at room temperature.
It contains elements but no molecular substances.
Its gases are not chemically bonded in one fixed ratio and can be separated physically.
Its composition is identical in every environment.
7. A particle model shows only identical units, and every unit consists of one type-A atom bonded to one type-B atom. What does the model represent?
A mixture of two elements
A pure compound
A mixture of two compounds
A pure element
8. Two samples of the same pure compound are tested under the same pressure. Which result is most expected?
They contain different element ratios because their sample sizes differ.
They have the same characteristic melting point and the same elemental ratio.
They can be separated into their elements by filtration.
They boil over broad, unrelated temperature ranges.
9. Which description correctly classifies pure water?
It is a homogeneous mixture because hydrogen and oxygen are evenly distributed.
It is a compound because hydrogen and oxygen are chemically bonded in a fixed proportion.
It is a heterogeneous mixture because it can exist as ice and liquid.
It is an element because all its particles are alike.
10. Which observation most strongly supports classifying a material as a mixture?
Every particle has the same arrangement of chemically bonded atoms.
The material has a single chemical formula and a fixed elemental ratio.
A chemical reaction is required to produce simpler substances from it.
Different samples can contain different proportions of the same components.
11. Which statement best distinguishes a compound from a mixture?
A compound always contains two elements, while a mixture must contain at least three substances.
A compound contains elements chemically bonded in a fixed ratio, while a mixture contains substances physically combined in variable proportions.
A compound is always solid at room temperature, while a mixture may be in any state.
A compound can be separated physically, while a mixture requires a chemical reaction to separate it.
12. An unknown liquid boils over a range of temperatures even though the pressure remains constant. Which interpretation is most reasonable?
It is likely a mixture whose components have different boiling points.
It must be a pure compound with a fixed composition.
It must be an element changing into a compound.
It is necessarily a suspension containing an insoluble solid.
13. A beaker contains sand mixed with salt water. Which sequence can recover dry sand and then obtain salt from the remaining liquid?
Decant the mixture and use a separating funnel to divide the dissolved salt from water.
Evaporate the entire mixture first, then use a magnet to remove the sand.
Use chromatography first, then filter the separated colors.
Filter the mixture, dry the residue, and evaporate water from the filtrate.
14. Iron filings and sulfur powder can initially be separated with a magnet. After they are strongly heated together, a new solid forms that is no longer separated this way. What is the best conclusion?
The heating produced a more finely divided mixture of iron and sulfur.
The iron changed state while the sulfur remained unchanged.
The sulfur dissolved in the iron without forming a new substance.
Iron and sulfur chemically combined to form a compound with new properties.
15. A black ink sample produces three distinct spots during paper chromatography. What does this most directly suggest?
The ink contains at least three components that move differently with the solvent.
The paper chemically changed the ink into three new elements.
The ink is a pure compound that decomposed on the paper.
The ink contains exactly three compounds in equal proportions.
16. Which process provides evidence that a substance is a compound rather than an element?
The substance is ground into a finer powder.
The substance melts and later freezes without forming new materials.
A chemical process breaks the substance into two simpler substances.
The substance dissolves evenly in water.