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Q1. Which mixture shows uniform composition?
Lemonade shows uniform composition because it is a homogeneous mixture. The sugar and lemon juice particles are evenly distributed throughout the water, so every sip tastes the same. Salt and sulphur, iron filings and sand, and oil and water are all heterogeneous mixtures with non-uniform composition.
Q2. A mixture with physically distinct parts is called
A mixture with physically distinct parts is called a heterogeneous mixture. In such mixtures, the different components can be seen separately and are not uniformly distributed. Examples include sand and water, oil and water, and salt and sulphur.
Q3. Lemonade is an example of
Lemonade is an example of a solution. It is a homogeneous mixture where sugar and lemon juice are completely dissolved in water. The particles are evenly distributed and cannot be seen separately. Solutions are uniform throughout.
Q4. The taste of a solution is the same throughout due to
The taste of a solution is the same throughout due to the uniform distribution of particles. In a solution, the solute particles are evenly spread throughout the solvent, so every part of the solution has the same composition and therefore the same taste.
Q5. Brass is a mixture of
Brass is an alloy made by mixing copper and zinc. It is a solid solution (homogeneous mixture) of these two metals. The composition of brass can vary, but typically it contains about 70% copper and 30% zinc.
Q6. Chalk powder in water forms a
Chalk powder in water forms a suspension. The chalk particles are insoluble and remain suspended in the water. When left undisturbed, the chalk particles settle at the bottom because they are larger and heavier than water particles.
Q7. Which mixture cannot be separated by physical methods?
Salt and water cannot be separated by physical methods like filtration because salt dissolves completely in water to form a solution. To separate them, we need to evaporate the water, which is a physical method, but the answer here refers to simple separation like filtration. Among the options, a true solution like salt and water cannot be separated by filtration. Alloys, colloids, and suspensions can be separated by physical methods.
Q8. Mixture of sodium chloride and iron filings is an example of
A mixture of sodium chloride (salt) and iron filings is heterogeneous because the components can be easily seen and distinguished. The white salt crystals and grey iron filings remain as separate phases and are not uniformly mixed at the particle level.
Q9. The major constituent of air is
The major constituent of air is nitrogen, which makes up about 78% of the atmosphere. Oxygen is about 21%, and other gases like carbon dioxide, argon, and water vapour are present in much smaller quantities.
Q10. In tincture of iodine, iodine is the
In tincture of iodine, iodine is the solute. It is the substance that is dissolved in the solvent. The solvent in tincture of iodine is alcohol (or a mixture of alcohol and water). Iodine is present in smaller amount, so it is the solute.
Q11. In a solution, homogeneity exists at the
In a solution, homogeneity exists at the particle level. The solute particles are uniformly distributed among the solvent particles at the molecular or ionic level. This means that any sample taken from the solution has the same composition as the whole.
Q12. Tincture of iodine contains iodine dissolved in
Tincture of iodine contains iodine dissolved in alcohol. It is a solution where iodine is the solute and alcohol is the solvent. This is used as an antiseptic. Iodine is not soluble in oil, and it dissolves better in alcohol than in water.
Q13. In gas in gas solution, both solute and solvent are
In a gas in gas solution, both the solute and the solvent are in the gaseous state. Air is an example of a gas in gas solution, where oxygen and other gases are dissolved in nitrogen, which acts as the solvent.
Q14. Air is a mixture of
Air is a mixture of gas in gas. It is a homogeneous mixture where various gases like oxygen, nitrogen, carbon dioxide, and argon are mixed together. Nitrogen is the major component and acts as the solvent, while other gases are solutes.
Q15. Which of the following is a solid solution?
Brass is a solid solution. It is an alloy made by dissolving zinc in copper (or vice versa). Both components are in the solid state, and they form a homogeneous mixture at the particle level. Milk is a colloid, soda water is a gas in liquid solution, and air is a gas in gas solution.
Q16. In sugar solution, water acts as
In a sugar solution, water acts as the solvent. It is the component present in larger amount and dissolves the sugar. The sugar is the solute. The solvent is the substance that does the dissolving.
Q17. Approximate composition of brass is
The approximate composition of brass is about 30% zinc and 70% copper. This composition gives brass its characteristic properties like good strength and corrosion resistance. The composition can vary depending on the type of brass.
Q18. In sugar solution, sugar acts as
In a sugar solution, sugar acts as the solute. It is the substance that is dissolved in the water (solvent). Sugar is present in smaller amount compared to water, making it the solute. It dissolves completely to form a homogeneous solution.
Q19. Alloys are considered mixtures because they
Alloys are considered mixtures because they have variable composition. Unlike compounds, which have a fixed chemical formula, the proportions of metals in alloys can be varied to achieve desired properties. Brass can have different ratios of copper and zinc.
Q20. The difference in colour intensity of copper sulphate solutions shows that
The difference in colour intensity of copper sulphate solutions shows that homogeneous mixtures can have variable composition. A more concentrated solution has a darker colour because more copper sulphate particles are present in the same volume. Both are still homogeneous solutions.
Q21. Oil and water mixture is heterogeneous because
Oil and water mixture is heterogeneous because they form layers. Oil is less dense than water and does not dissolve in it, so the two liquids remain as separate phases. This is why oil and water are easily distinguishable and do not mix uniformly.
Q22. Air is considered a
Air is considered a homogeneous mixture because its components (gases) are uniformly distributed throughout. You cannot see separate layers or phases in the air. Even though air contains different gases, they are mixed at the molecular level, making it homogeneous.
Q23. Which of the following is a heterogeneous mixture?
Oil and water is a heterogeneous mixture because they do not mix and form separate layers. Soda water, air, and lemonade are all homogeneous mixtures where the components are evenly distributed. Oil and water have a non-uniform composition.
Q24. Aerated drinks contain which gas as solute?
Aerated drinks contain carbon dioxide gas as the solute. The gas is dissolved in the liquid (water) under high pressure, forming a gas in liquid solution. This is what gives aerated drinks their fizz and bubbles.
Q25. A solution is a
A solution is a homogeneous mixture. It has a uniform composition throughout, and the particles of the solute are evenly distributed among the particles of the solvent. Solutions can be solid, liquid, or gas.
Q26. Percentage of nitrogen in air is approximately
The percentage of nitrogen in air is approximately 78%. This is the largest component of air. Oxygen makes up about 21%, and the remaining 1% includes argon, carbon dioxide, and other gases.
Q27. The component dissolved in a solution is called
The component dissolved in a solution is called the solute. It is the substance present in smaller amount that gets dissolved in the solvent. For example, in sugar solution, sugar is the solute and water is the solvent.
Q28. Percentage of oxygen in air is approximately
The percentage of oxygen in air is approximately 21%. This is the second largest component of air after nitrogen. Oxygen is essential for respiration and combustion. The remaining percentage is made up of other gases.
Q29. Solutions always consist of at least
Solutions always consist of at least two substances: a solute and a solvent. A solution cannot be made of a single substance because it requires at least one substance to dissolve in another. Air is a solution of several gases, all in the same state.
Q30. Which mixture shows same properties throughout?
A solution shows the same properties throughout because it is a homogeneous mixture. Any sample taken from a solution has the same composition and properties as the whole. Suspensions and heterogeneous mixtures have different properties in different parts.
Q31. A suspension is formed when particles
A suspension is formed when particles settle on standing. The particles in a suspension are larger and heavier, so they do not remain suspended indefinitely. When left undisturbed, they settle to the bottom due to gravity. This is a characteristic property of suspensions.
Q32. Colloidal solutions have particles that are
Colloidal solutions have particles that are intermediate in size—larger than molecules in a true solution but smaller than particles in a suspension. These particles scatter light (Tyndall effect) and do not settle on standing. They are not visible to the naked eye.
Q33. Heterogeneous mixtures have
Heterogeneous mixtures have non-uniform composition. This means that different parts of the mixture have different properties and composition. For example, in a mixture of sand and salt, one part may have more sand while another has more salt.
Q34. Groups A and B obtained
Groups A and B obtained a solution (based on typical class experiments). When soluble substances like salt or sugar are dissolved in water, they form true solutions which are clear and homogeneous. The particles cannot be seen and do not scatter light.
Q35. Milk is an example of
Milk is an example of a colloid. It is a colloidal solution where fat globules are dispersed in water. The particles are intermediate in size and scatter light (Tyndall effect), making milk appear opaque. The particles do not settle on standing.
Q36. Group C obtained
Group C obtained a colloid (based on typical class experiments). Substances like starch or milk in water form colloidal solutions. The particles are intermediate in size, do not settle, and scatter light.
Q37. Sugar in water is an example of
Sugar in water is an example of a solid in liquid solution. The solute (sugar) is in the solid state, and the solvent (water) is in the liquid state. The sugar dissolves completely to form a homogeneous mixture.
Q38. A mixture having non-uniform composition is called
A mixture having non-uniform composition is called a heterogeneous mixture. In such mixtures, the components are not evenly distributed and can be seen separately. Examples include sand and water, oil and water, and salt and sulphur.
Q39. Soda water is an example of
Soda water is an example of a gas in liquid solution. Carbon dioxide gas (the solute) is dissolved in water (the solvent) under pressure. This forms a homogeneous mixture where the gas is evenly distributed throughout the liquid.
Q40. A mixture of salt and sulphur is
A mixture of salt and sulphur is heterogeneous. The white salt crystals and yellow sulphur powder are easily distinguishable and do not form a uniform mixture. The components remain separate and can be seen with the naked eye.
Q41. Which of the following is NOT a solution?
Chalk powder in water is NOT a solution. It is a suspension because the chalk particles do not dissolve and settle at the bottom when left undisturbed. Air, lemonade, and soda water are all true solutions.
Q42. Soda water is an example of
Soda water is an example of a gas in liquid solution. Carbon dioxide gas is dissolved in water (the liquid solvent) under pressure. This is a homogeneous mixture where the gas is uniformly distributed.
Q43. Which of the following is NOT usually thought of as a solution?
Suspension is NOT usually thought of as a solution. In a suspension, the particles are not dissolved but are suspended in the medium and settle on standing. Solutions are homogeneous mixtures where the solute is completely dissolved, regardless of the states involved.
Q44. Lemonade tastes the same throughout because
Lemonade tastes the same throughout because the sugar particles are evenly distributed in the water. This uniform distribution is a characteristic of solutions (homogeneous mixtures). Every sip of lemonade has the same concentration of sugar and lemon juice.
Q45. Variable composition is a property of
Variable composition is a property of mixtures. Unlike compounds, which have a fixed chemical formula (e.g., H₂O for water), mixtures can have any proportion of their components. For example, sugar solution can be made with more or less sugar in the same amount of water.
Q46. The component present in larger amount in a solution is called
The component present in larger amount in a solution is called the solvent. It is the substance that dissolves the solute. In a sugar solution, water is the solvent because it is present in larger quantity and dissolves the sugar.
Q47. Homogeneous mixtures appear
Homogeneous mixtures appear uniform throughout. This means that any sample taken from the mixture has the same composition and properties as any other sample. This uniformity is a defining characteristic of homogeneous mixtures.
Q48. Other gases(besides nitrogen and oxygen) in air are present in
Other gases in air (besides nitrogen and oxygen) are present in small quantities. These include argon, carbon dioxide, neon, helium, and other trace gases. They make up less than 1% of the atmosphere by volume.
Q49. Which statement is correct about solutions?
The correct statement about solutions is that they can be solid, liquid, or gas. Solutions exist in all three states of matter. Examples include: liquid solutions (sugar in water), solid solutions (alloys like brass), and gas solutions (air).