Students can download Class 8 Science Chapter 16 States of Matter Important Questions, KSEEB Class 8 Science Important Questions and Answers helps you to revise the complete Karnataka State Board Syllabus and to clear all their doubts, score well in final exams.
Karnataka State Syllabus Class 8 Science Important Questions Chapter 16 States of Matter
Question 1.
What is matter?
Answer:
Anything that has mass and occupies space is called matter.
Question 2.
What are the states in which matter usually exists?
Answer:
Matter usually exists in three states namely solid state, liquid state and gaseous state.
Question 3.
Make a list of materials around us and classify them as solids, liquids and gases. Write your answers in a tabular column.
Answer:
Question 4.
List some of the general properties of matter in solid state.
Answer:
The properties of solids are as follows:
- All substances in solid state have definite shape and volume.
- The molecules in a solid are closely packed. The distance between the molecules is very small. Therefore solids cannot be easily compressed.
- Matter in solid state cannot flow. Molecules have the least mobility.
- The attraction between the molecules is strongest in solids.
- Matter in solid state usually turns into liquid or vapour state on heating.
Question 5.
List some of the general properties of materials in liquid state.
Answer:
The properties of liquids are as follows:
- Matter in liquid state has definite volume but not definite shape. It takes the shape of the containing vessel.
- The distance between molecules is higher than that in solids but lower thhn that in gases.
- Liquids can easily flow.
- Matter in liquid state cannot easily be compressed.
- The molecules in liquid state have greater mobility than those in solids.
Question 6.
List the characteristics of matter in gaseous state.
Answer:
Matter in gaseous state has the following characteristics:
- Gases have neither definite shape nor definite volume. Matter in gaseous state takes the shape of the container.
- The distance between molecules is highest for gases.
- The molecules of matter in gaseous state can be easily compressed.
- The molecules have the highest kinetic energy and hence are found be in a state of random motion.
Question 7.
Gases do not have definite shape and volume. Give reason.
Answer:
The particles in a gas have very high kinetic energy and high distance between molecules. Therefore, they occupy all the space available to them and they can be easily compressed by applying pressure. Hence gases have neither definite shape nor definite volume.
Question 8.
Distinguish between solid state, liquid state and gaseous state of matter in terms of
- Arrangement of particles
- Shape
- Volume
- Compressibility
- Density.
Answer:
Question 9.
How are substances classified on the basis of their purity?
Answer:
Substances are broadly classified on the basis of their purity into two types as
- pure substances
- impure substances.
Question 10.
What is a pure substance?
Answer:
A substance whose constituent particles are all identical chemically is called a pure substance.
Question 11.
Give an example of a pure substance. Explain why it is considered pure.
Answer:
Distilled water is a pure substance. This is because it contains only one type of chemical particles (H2O) only.
Question 12.
What is an impure substance? Give an example.
Answer:
Any substance composed of two or more types of chemical particles is considered an impure substance. For example, fruit juice is not a pure substance as it is made up of more than one type of chemical particles. Similarly, sea water is not a pure substance.
Question 13.
Classify the following as pure substances and impure substances: Sea water, sugar, distilled water, milk, copper, tap water.
Answer:
- Pure substances: Sugar, distilled water, copper
- Impure substances: Sea water, milk, tap water.
Question 14.
What is a mixture? Give an example.
Answer:
A mixture is a substance formed when two or more substances are combined such that each substance retains its own separate chemical identity. eg. 22 carat gold is a mixture of gold and copper.
Question 15.
List the properties of mixtures.
Answer:
The properties of mixtures include the following:
- The properties of a mixture depend on the properties of its constituents.
- There is no chemical change during the formation of a mixture.
- Mixture has no fixed chemical composition.
- The constituents of a mixture can usually be separated by a simple physical process.
Question 16.
Why is air called a mixture?
Answer:
Air is not a single pure substance. It is formed by the physical mixing of oxygen, nitrogen, carbon dioxide and other gases. Hence it is called a mixture.
Question 17.
Are the properties of mixtures and compounds one and the same? Discuss.
Answer:
No, the properties of mixtures and compounds are not one and the same. The properties of a mixture are determined by the properties of the constituent substances. The properties of a compound are different from the properties of the constituent elements. For example, the properties of a mixture of hydrogen and oxygen depend on the properties of both hydrogen and oxygen.
Hydrogen is a combustible gas and oxygen is a supporter of combustion. This mixture gets ignited easily by a splinter. Water is a compound formed by the chemical union of hydrogen and oxygen. Water is not a combustible substance. It actually extinguishes fire.
Question 18.
Sodium chloride is made of two pure substances namely sodium and chlorine. Is sodium chloride a mixture? Why?
Answer:
Sodium chloride is not a mixture. It is a pure substance which is made of only one kind of particles. Hence it is not a mixture.
Question 19.
Why is milk considered a mixture?
Answer:
Milk is actually a combination of water, fat, proteins etc. Thus milk consists of more than one kind of chemical particles (sodium chloride molecules). Hence milk is considered a mixture.
Question 20.
Classify the following as pure substances and mixtures: copper, sea water, ice, common sugar, soil, soft drink.
Answer:
- Pure substances: Copper, ice, common sugar.
- Mixtures: Sea water, soil, soft drink.
Question 21.
Which of the following materials are pure substances: ice, milk, mercury, calcium oxide, brick, mud, wood, air, iron, hydrochloric acid?
Answer:
Pure substances among the given are ice, mercury, calcium oxide, iron and hydrochloric acid. The others are mixtures.
Question 22.
Why are alloys called mixtures?
Answer:
An alloy is formed by the physical mixing of two or more metals in any proportion. There is no chemical union between the constituents of the alloy. This is why alloys are called mixtures.
Question 23.
How are mixtures classified on the basis of their appearance and distribution?
Answer:
Mixtures are broadly classified on the basis of their appearance and distribution into two types
- Homogeneous mixtures
- Heterogeneous mixtures.
Question 24.
What is a homogeneous mixture? Give two examples.
Answer:
A mixture is called a homogeneous mixture if its components are uniformly distributed throughout and are not easily distinguishable even under a microscope. eg. Sugar solution, brine solution, salt solution, metal alloys, air etc.
Question 25.
Ornamental gold is an example for homogeneous mixture. Give scientific reason.
Answer:
Ornamental gold contains some amount of copper. However, gold and copper do not appear distinctly in it. This is why ornamental gold is considered a homogeneous mixture.
Question 26.
What is a heterogeneous mixture? Give two examples.
Answer:
A mixture in which the different constituents do not mix uniformly is called a heterogeneous mixture. The components of the mixture are visible to the naked eye and it is comparatively easy to separate them. eg: Mixture of salt and copper sulphate, mixture of water and oil etc.
Question 27.
A mixture of sand and iron filings is a heterogeneous mixture. Give reason.
Answer:
In a mixture of sand and iron filings, the constituent substances are uniformly distributed and are easily distinguishable. Hence it is a heterogeneous mixture.
Question 28.
Classify the following as homogeneous mixtures and heterogeneous mixtures: soda water, wood, air, soil, vinegar, filtered tea, mixture of salt and copper sulphate, mixture of water and oil.
Answer:
Homogeneous mixtures: Soda water, air, vinegar, filtered tea, mixture of water and oil.
Heterogeneous mixtures: Soil and wood, mixture of salt and copper sulphate.
Question 29.
List the points of differences between homogeneous mixtures and heterogeneous mixtures.
Answer:
Homogeneous mixtures:
- The constituents are uniformly distributed throughout.
- The constituents are not physically distinguishable.
Heterogeneous mixtures:
- The constituents are not uniformly distributed throughout the mixture.
- The constituents are physically distinguishable.
Question 30.
Differentiate between homogeneous and heterogeneous solutions with an example each.
Answer:
Homogeneous mixture:
It is one in which the components are uniformly distributed throughout and are not easily distinguishable even under a microscope. eg. Sugar solution.
Heterogeneous mixture:
whose constituents do not mix uniformly and are easily distinguishable is called a heterogeneous mixture. eg. Mixture of water and oil.
Question 31.
Give two examples for each of the following types of mixtures
- A homogeneous mixture of solid and solid
- A heterogeneous mixture of solid and solid
- A heterogeneous mixture of solid and liquid
- A homogeneous mixture of liquid and gas
- A homogeneous mixture of gas and gas.
Answer:
- A homogeneous mixture of solid and solid: Bronze, stainless steel.
- A heterogeneous mixture of solid and solid: Mixture of salt and copper sulphate, mixture of sand and iron filings.
- A heterogeneous mixture of solid and liquid: A mixture of saw dust in water, a mixture of sulphur in water.
- A homogeneous mixture of liquid and gas: Moisture in air, deodorant sprays.
- A homogeneous mixture of gas and gas: Mixture of oxygen and nitrogen.
Question 32.
Explain the meaning of the following terms: solution, solute and solvent. Give an example.
Answer:
1. Solution:
A homogeneous mixture of two or more substances is called a solution.
2. Solute:
A substance that is dissolved in another substance is called a solute. In a homogeneous mixture of two or more substances, the substance present in smaller quantities is called the solute.
3. Solvent:
A substance that dissolves another substance in it is called a solvent. In a homogeneous mixture of two or more substances, the substance present in largest quantity is called the solvent.
4. Example:
Consider a homogeneous mixture of sugar and water wherein sugar is dissolved in water. Here, sugar is the solute, water is the solvent and the homogeneous mixture formed is called solution.
Question 33.
Which are the components of a solution?
Answer:
A solution consists of a solvent and one or more solutes as its constituents.
Question 34.
In sugar solution, which is the solute and which is the solvent?
Answer:
In sugar solution, sugar is the solute and water is the solvent.
Question 35.
In a solution of two or more substances, how do you identify the solute(s) and the solvent?
Answer:
In a solution of two or more substances, the substance which is present in the largest quantity is the solvent. Those substances that are present in relatively smaller quantities are called solutes.
Question 36.
Water is called a universal solvent. Give reason.
Answer:
Water can dissolve in it largest number of substances. Hence it is called a universal solvent.
Question 37.
Give any two examples of solvents other than water.
Answer:
Carbon tetrachloride, carbon disulphide, petrol and kerosene are a few examples of solvents other than water.
Question 38.
Give a suitable solvent for the following: iodine, paint, nail polish and rubber.
Answer:
Iodine dissolves in carbon tetrachloride and carbon disulphide. Paint dissolves in turpentine oil. Nail polish dissolves in acetone. Rubber dissolves in petrol.
Question 39.
List the various types of solutions. Give an example each.
Answer:
| Type of solution | Example |
| 1. Solid in liquid | Sugar solution |
| 2. Liquid in liquid | A mixture of alcohol and water |
| 3. Gas in liquid | Soda water |
| 4. Gas in gas | Air |
| 5. Solid in solid | Alloys |
Question 40.
Identify the solvent and solute in
- aerated drinks
- tincture of iodine
- air
- seawater.
Answer:
Question 41.
What is meant by solubility?
Answer:
The amount of a substance (solute) that can dissolve in a given amount of another substance (solvent) is called solubility of that substance.
Question 42.
List the properties of a solution.
Answer:
- A solution is a homogeneous mixture of two or more substances.
- The particles of a solution are very very small and hence are invisible to the naked eye.
- The particles of a solution are so small that they cannot scatter light.
- The particles of a solution cannot be separated by filtration.
Question 43.
What is meant by saturated solution?
Answer:
A solution which has dissolved as much solute as it is capable of dissolving at a given temperature is said to be a saturated solution at that temperature.
Question 44.
What is meant by unsaturated solution?
Answer:
A solution that has dissolved less solute than what it is capable of dissolving at a given temperature is called an unsaturated solution.
Question 45.
How can you make more solute to dissolve in a saturated solution?
Answer:
We can make more solute to dissolve in a saturated solution by increasing the temperature of the solution.
Question 46.
Describe a simple activity to prepare a saturated solution of sodium chloride.
Answer:
Take about 50 mL of water in a beaker. Add sodium chloride (common salt) to water and keep stirring. When no more salt can be’dissolved, stop stirring. Decant the contents to another beaker. This is a saturated solution of sodium chloride at room temperature.
Question 47.
What is a suspension? Give an example.
Answer:
A suspension is a heterogeneous mixture in which the solid particles do not dissolve but remain suspended throughout the bulk of the liquid medium. eg: Muddy water.
Question 48.
List the properties of a suspension.
Answer:
- Suspension is a heterogeneous mixture.
- The particles in a suspension are large enough to be seen with the naked eye.
- When a suspension is left undisturbed for some time, the suspended particles settle down.
- A suspension scatters light.
Question 49.
What is suspension medicine? Give two examples.
Answer:
A suspension medicine is a liquid in which small amount of a drug remains in suspension. The drug is not completely dissolved in the solution. The bottles containing such medicine should be shaken or stirred well before we take them.
This ensures that we take the right amount of drug each time. eg: Insulin and Antibiotic suspensions such as Amoxicillin are two examples of suspension medicines.
Question 50.
What is a colloidal solution? Give two examples.
Answer:
A colloidal solution is a solution in which a material is evenly suspended in a liquid. eg: Milk, starch solution, protoplasm etc.
Question 51.
Distinguish between dispersed phase and dispersing medium with respect to colloids.
Answer:
- Dispersed phase: The colloidal particles which are distributed in a medium are known as dispersed phase.
- Dispersing medium: The continuous medium, such as a gas, a liquid, or a solid, in which colloidal particles are uniformly distributed is called the dispersing medium (dispersion medium).
Question 52.
List the properties of a colloidal solution.
Answer:
- Colloidal solutions are heterogeneous mixtures.
- The particles of a colloid are too small to be seen with the naked eye.
- Colloidal particles scatter light.
- Colloids are stable and do not settle down on standing.
- The particles of a colloid are uniformly spread throughout the solution.
Question 53.
What is Tyndall effect? Illustrate with an example.
Answer:
The phenomenon of scattering of light by colloidal particles is called Tyndall effect. The visible beam of light from headlights of vehicles in fog is caused by the Tyndall effect. The water droplets scatter the light, making the headlight beams visible.
Question 54.
Which of the following will show Tyndall effect: Salt solution, Milk, Copper sulphate solution, Starch solution?
Answer:
Tyndall effect is shown by colloidal solutions whose suspended particles are microscopic or of very small size. From among the given substances, only milk and starch solution are colloids and they show Tyndall effect. Salt solution and copper sulphate solution are true solutions and they do not show Tyndall effect.
Question 55.
Give two examples of Tyndall effect in colloidal solutions.
Answer:
The Tyndall effect can be observed when the sunlight passes through the canopy of a dense forest. The tiny droplets of water present in mist are colloidal particles and scatter light. A beam of bright light becomes visible in a smoke filled room. This is due to the Tyndall effect caused by the scattering of light particles present in smoke.
Question 56.
When a beam of light is passed through a suspension, its path becomes visible. Give reason.
Answer:
Suspensions contain particles which are big enough to scatter light. Such scattering is known as Tyndall effect. When a beam of light is passed through a suspension, the particles present in it scatter light in different directions and make the path visible.
Question 57.
List the various types of colloids. Give two examples for each type.
Answer:
Colloids are classified into various types as aerosols, foam, emulsion, sol, foam, gel and solid gel. Phis classification is made on the basis of the physical state of the dispersion medium and the dispersed phase. The types of colloids and examples are listed in the table below:
Question 58.
What is Brownian movement? What causes it?
Answer:
The particles of a colloidal solution are in a state of constant random motion in a liquid or gas medium. Such motion of particles is known as Brownian movement. Brownian movement is caused by the collision of the suspended particles with the molecules of the dispersion medium.
Multiple Choice Questions
Question 1.
Which of the following does not hold good for liquids?
(a) They have definite volume.
(b) They are slightly compressible than solids.
(c) Molecules are free to move within the substance.
(d) They have definite shape and size.
Answer:
(d) They have definite shape and size.
Question 2.
Which of the following is not a pure substance?
(a) Common salt
(b) Sugar
(c) Pond water
(d) Iron.
Answer:
(c) Pond water
Question 3.
The component which is not present in air is
(a) nitrogen
(b) oxygen
(c) carbon dioxide
(d) chlorine.
Answer:
(d) chlorine.
Question 4.
Butter is an example for
(a) liquid in solid
(b) solid in liquid
(c) liquid in liquid
(d) solid in solid
Answer:
(a) liquid in solid
Question 5.
Which one of the following is true with respect to gases?
(a) Gases have neither definite shape nor definite volume.
(b) Gases have definite shape but not definite volume.
(c) Gases have definite volume but not definite shape.
(d) Gases have definite shape and definite volume.
Answer:
(a) Gases have neither definite shape nor definite volume.
Question 6.
Which one of the following shows Tyndall effect?
(a) Sodium chloride solution
(b) Sugar solution
(c) Milk
(d) Copper sulphate solution
Answer:
(c) Milk
Question 7.
A heterogeneous mixture among the following is
(a) sugar solution
(b) mixture of water and oil
(c) sea water
(d) aerated drinks.
Answer:
(b) mixture of water and oil
Question 8.
Brass is a
(a) compound
(b) pure substance
(c) homogeneous mixture
(d) heterogeneous mixture
Answer:
(c) homogeneous mixture
Question 9.
An example of a colloidal solution is
(a) milk
(b) alloys
(c) drinking soda
(d) a mixture of sawdust and chalk dust
Answer:
(a) milk
Question 10.
Which one of the following does not show Brownian movement?
(a) Milk
(b) Aerosols
(c) Smoke
(d) Salt solution.
Answer:
(d) Salt solution.
Fill In The Blanks
1. The state of matter in which the inter-molecular force of attraction is highest is solid state
2. The state of matter that has neither definite volume nor shape is gaseous state
3. The state of matter in which the substance takes the shape of the container is liquid state
4. The state of matter in which the particles have highest kinetic energy is gaseous state
5. The random motion of the particles of a colloidal solution is known as Brownian movement
6. The scattering of light by the particles of a colloidal solution is called Tyndall effect
Match The Following
| A | B |
| 1. Sodium chloride | (a) Impure substance |
| 2. Milk | (b) Suspension solution |
| 3. Air | (c) Pure substance |
| (d) Mixture |
Answer:
1 – c, 2- b, 3 – d.