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Quizzes > Science

Composition of Mixtures Practice Problems Quiz

Quick mixture composition quiz to test your knowledge. Instant results.

Editorial: Review CompletedCreated By: Claudia James Mcdermott Es CounselorUpdated Aug 25, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art style beakers flasks molecules elements compounds icons quiz composition of mixtures golden yellow background

This quiz helps you practice the composition of mixtures by sorting elements, compounds, and mixtures and reading how parts combine. Get instant feedback to spot gaps and build speed for class or tests. For more help, try our homogeneous and heterogeneous mixtures quiz, the mixtures and pure substances quiz, or the mixtures and solutions quiz.

What distinguishes a compound from an element?
It consists of two or more elements chemically bonded.
It is always a gas at room temperature.
It contains only one type of atom.
It can be separated into its elements by physical means.
A compound consists of two or more elements that are chemically bonded in fixed proportions, while an element is a pure substance made of one type of atom. Compounds have distinct chemical properties from the constituent elements. They require chemical reactions to be broken down. For more details see .
Which of the following is an example of a homogeneous mixture?
Sugar dissolved in water
Mixed nuts
Oil and water
Beach sand
A homogeneous mixture has a uniform composition throughout. When sugar dissolves in water, the sugar molecules disperse evenly, creating a single-phase solution. You cannot distinguish the sugar from the water by simple observation. See for more information.
Which process is classified as a physical change?
Digesting food
Rusting iron
Burning wood
Melting ice
A physical change alters the form or state of a substance without changing its chemical identity. Melting ice turns solid water into liquid water, but the substance remains H?O. In contrast, rusting and burning involve new substances forming. For a deeper explanation see .
Which of the following is an example of a chemical change?
Salt dissolving in water
Water freezing
Sugar melting
Iron rusting
A chemical change produces one or more new substances with different properties. Iron rusting forms iron oxide from elemental iron and oxygen in the air. This process cannot be reversed by simple physical methods. Learn more at .
Which of the following best describes an alloy?
A chemically bonded compound of metals
A solution of metal ions in water
A salt crystal
A homogeneous solid mixture of two or more metals
An alloy is a homogeneous solid mixture composed of two or more metals, or a metal and another element, mixed at the atomic level. Alloys have properties distinct from their component elements. They are not compounds because the metals are not chemically bonded in fixed ratios. See for details.
Chalk, which is calcium carbonate (CaCO?), is classified as which type of substance?
Element
Mixture
Colloid
Compound
Calcium carbonate is composed of the elements calcium, carbon, and oxygen in a fixed chemical ratio, so it is a compound. Mixtures have variable compositions, and elements consist of only one type of atom. Colloids are mixtures where microscopically dispersed particles remain suspended. More information at .
Which separation technique would you use to obtain pure water from a saltwater solution?
Distillation
Centrifugation
Filtration
Chromatography
Distillation separates substances based on differences in boiling points. Saltwater is heated until water vaporizes, then the vapor is condensed to yield pure water, leaving salt behind. Filtration can remove solids but not dissolved salts. Refer to for more.
What is the most effective way to separate a mixture of oil and water?
Paper chromatography
Decanting
Centrifugation
Evaporation
Decanting or using a separatory funnel allows the less dense oil to float on top of the denser water, enabling easy phase separation by pouring off one layer. Evaporation would remove water but could leave behind residues. Chromatography is not practical for bulk separation of liquids. More at .
If a compound is 40% carbon by mass, how many grams of carbon are in a 50 g sample?
25 g
10 g
40 g
20 g
Percent composition by mass means 40 g of carbon per 100 g of compound. For a 50 g sample, (40/100)×50 equals 20 g of carbon. This calculation is fundamental for determining empirical formulas. For more see .
A compound has the following percent composition: 52.14% C, 34.73% O, and 13.13% H. What is its empirical formula?
CH2O
C2H3O
C2H6O
C3H8O
Assume 100 g: C=52.14 g/12.01=4.34 mol, H=13.13 g/1.008=13.03 mol, O=34.73 g/16.00=2.17 mol. Dividing by smallest (2.17) gives ratios of C2, H6, O1, so empirical formula C2H6O. Review for details.
You have a mixture of sand, salt, and water. Which sequence of processes will yield dry salt?
Distillation then decanting
Filtration then evaporation
Evaporation then filtration
Chromatography then filtration
First, filtration removes the insoluble sand from the saltwater solution. Then evaporation of water leaves behind dry salt crystals. Distillation would also work but is less practical on a small lab scale, and chromatography is unsuitable for bulk separation. See .
Which of these mixtures is heterogeneous?
Air
Muddy water
Brass
Salt solution
Muddy water contains visible solid particles dispersed in liquid, making it heterogeneous. Brass and air are homogeneous mixtures (an alloy and a gas mixture, respectively), and a salt solution is uniform throughout. Heterogeneous mixtures have non-uniform composition. More at .
A compound is 40% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. Its empirical formula is CH?O. If its molar mass is about 180 g/mol, what is its molecular formula?
C6H12O6
CH2O
C3H6O3
C2H4O2
The empirical formula mass of CH?O is about 30 g/mol. Dividing the molar mass (180 g/mol) by 30 g/mol gives 6, so the molecular formula is (CH?O)? or C?H??O?. This process determines actual formulas from empirical data. See for further reading.
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Study Outcomes

  1. Understand Physical and Chemical Changes -

    Learn to distinguish between physical and chemical transformations by exploring key characteristics in our physical and chemical change quiz. This outcome helps reinforce your grasp of how matter behaves under different conditions.

  2. Identify Elements, Compounds, and Mixtures -

    Develop the ability to recognize and label substances as elements, compounds, or mixtures using targeted element compound mixture quiz questions. You'll master core definitions and properties for accurate classification.

  3. Differentiate Homogeneous and Heterogeneous Mixtures -

    Analyze examples of uniform and non-uniform mixtures to pinpoint distinguishing features. By practicing chemistry mixture practice questions, you'll confidently tell the difference between solution types.

  4. Apply Composition of Matter Classification -

    Use hands-on composition of mixtures practice problems to categorize real-world samples, reinforcing your understanding of matter's composition. This outcome ensures you can sort substances with precision.

  5. Analyze Mixture Practice Questions -

    Engage with scenario-based problems to test your reasoning skills in our chemistry composition of matter quiz. Immediate feedback helps you spot and correct misconceptions.

  6. Evaluate Separation Techniques -

    Explore common methods for separating mixtures, such as filtration and distillation, and assess their effectiveness. Integration with identify mixtures and compounds practice will deepen your practical knowledge.

Cheat Sheet

  1. Mixtures vs. Compounds -

    On composition of mixtures practice problems, remember that mixtures are physical blends of substances (like saltwater) and can be separated by physical means, whereas compounds (like NaCl) result from chemical bonding with fixed formulas. Mixtures have variable composition, but compounds obey the law of definite proportions. A neat mnemonic: "Mix and match, compound stays exact."

  2. Homogeneous vs. Heterogeneous -

    Homogeneous mixtures (solutions) have uniform composition at the molecular level (e.g., sugar dissolved in water), while heterogeneous mixtures (suspensions) display distinct phases (e.g., oil and water). The Tyndall effect - light scattering by colloidal particles - is a quick test for heterogeneity (think milk vs. water). Recall "homo same, hetero different" on element compound mixture quiz items.

  3. Physical vs. Chemical Changes -

    Physical changes alter state or appearance without forming new substances (melting ice), whereas chemical changes produce new products (rusting iron). On any physical and chemical change quiz, watch for bond breakage/formation and energy release or absorption. Use the mnemonic "Phase stays, chemistry plays" to cue transformation type.

  4. Elements vs. Compounds Identification -

    Elements consist of one type of atom (O₂, Fe), while compounds combine two or more elements in fixed ratios (H₂O, CO₂). Leverage the periodic table to match symbols and write formulas - Al³❺ + O²❻ → Al₂O₃ is a classic example. Practice with identify mixtures and compounds practice to solidify formula-writing skills.

  5. Key Separation Techniques -

    Common methods for breaking down mixtures include filtration (sand-water), distillation (ethanol-water), and chromatography (ink separation). Distillation exploits boiling point differences, while chromatography uses adsorption and polarity to resolve complex mixtures. Remember FDC - Filter, Distill, Chromatograph - as your go-to trio during chemistry mixture practice questions.

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