Matter Class-8 Dalal Simplified ICSE Chemistry Solutions Chapter-1

Matter Class-8 Dalal Simplified ICSE Chemistry Solutions Chapter-1, Matter Dr Viraf J Dalal Middle School Allied Publishers Solutions. Chapter-1. We Provide Step by Step Solutions to Questions and Answers of Dr Viraf J Dalal Middle School Chemistry Allied Publishers. Visit official Website CISCE for detail information about ICSE Board Class-8.

Matter Class-8 Dalal Simplified ICSE Chemistry Solutions Chapter-1

Exercise-1

Matter Class-8 Dalal Simplified ICSE Chemistry Solutions Chapter-1

Question: 1. Explain the meaning of the term ‘matter’.

Answer: Matter is anything which has mass and occupies space and can be felt by our senses.

For example, Chair, table, book, air, etc.

Question: 2. Matter in any state is composed of small particles – molecules, atoms or ions. Differentiate the terms above in italics.

Answer: Matter in any state is composed of small particles – molecules, atoms, or ions. Differentiate the terms above in Italics.

Molecules: A molecule is the smallest particle of a substance that can normally exist separately and retain the characteristics of the substance, e.g. O₂, H₂, Cl₂ are molecules.
Atoms: An atom is the smallest particle of an element that can take part in a reaction and is considered the basic unit of matter, e.g. O, H, Cl are atoms.
Ions: An ion is any atom or a group of atoms that has a resultant charge due to loss or gain of electrons, e.g. O^2-, H¹⁺, Cl^1-– are ions.

Question: 3. Differentiate between the two characteristics of matter – ‘mass’ and ‘weight’.

Answer: 

Question: 4. State which of the three states of matter i.e. solids, liquids or gases – have 

a] No definite volume

b] A definite shape

c] High density

d] No free surfaces

e] Particles – which diffuse very easily

Answer: (a) Gases
(b) Solids
(c) Solids
(d) Gases
(e) Gases

Question: 5. State the main postulates of the kinetic theory with special reference to –

a] Inter-particle space

b] Inter-particle attraction

c] Energy possessed by particles of matter

Answer: The postulates of kinetic theory of gases:

a) Interparticle space:  Particles of matter have spaces between them and these spaces are called intermolecular spaces. Intermolecular spaces depend on the intermolecular force of attraction between the particles, therefore, these spaces are different in solids, liquids, and gases. In solids intermolecular spaces are very less or negligible, liquids have moderate intermolecular spaces and gases have the highest intermolecular spaces.

b) Interparticle attraction: Particles of matter attract each other with a force of attraction called intermolecular force of attraction. The intermolecular force of attraction depends upon the distance between the particles, the higher the distance between the particles, the lesser will be the force of attraction and the lesser the distance between the molecule, the higher will be the force of attraction. The intermolecular force of attraction is highest in solids, moderate in liquids and least in gases.

c) Energy posses by particles of matter: The energy posses by the molecules depends on the random motion of particles. Since gases have the weakest intermolecular force of attraction, therefore, molecules can move easily and gain kinetic energy. Therefore gases have high energy.

Question: 6. State in which of the following examples i.e. piece of wood, water, a light gas is the –

a] Inter-particle space maximum

b] Inter-particle attraction maximum

c] Energy possessed by particles of matter, very large

Answer: The interparticle space is minimum in solid as the interparticle force of attraction is maximum in solid. Liquid has more interparticle space than solid and gases have maximum interparticle space.
(i) A light gas (1 Mark)
(ii) a piece of wood (1 Mark)
(iii) a light gas (1 Mark)

Question: 7. In which of the three states of matter – solids, liquids or gases is the movement of atoms about their own position. Give a reason for the same.

Answer: In solids, the movement of atoms or molecules takes place about their own position because of minimum intermolecular space and strong intermolecular force of attraction.

Since molecules are closely compact with each other, therefore the free movement of atoms or molecules is restricted.

Question: 8. ‘Inter-particle attraction between atoms of gases is very weak’. State five properties of gases which correlate as a consequence of the weak inter-particle attraction between particles of gases.

Answer: i) Gases are highly compressible: Due to the least interparticle force of attraction particles are very far away from each other, therefore gases are highly compressible.

ii) Gases have the tendency to flow: Due to the least interparticle force of attraction, particles are very far away from each other and can move easily.

iii) Gases do not have fixed volume: Due to the least interparticle force of attraction particles are very far away from each other, therefore they can be compressed to a great extent.

iv) Gases are the least rigid: Due to the least interparticle force of attraction, particles are very far away from each other and can move easily.

v) Gases diffuses easily: Due to the least interparticle force of attraction, particles are very far away from each other ,Therefore the kinetic energy of the particle is very high hence they diffuses fast.

Question: 9. What is inter-conversion of matter. Give the meaning of the terms involved in inter-conversion of matter –

a] Melting

b] Vaporisation

c] Liquefaction or condensation

d] Solidification or freezing

e] Sublimation

Answer: INTERCONVERSION OF MATTER :

“Change of state of matter from one state to another state and back to its original state is called inter-conversion of matter.”

(a) MELTING: Conversion of a solid into a liquid on heating e.g. ice to water.

(b) VAPORISATION: Conversion of a – liquid into vapours (or gas) on heating e.g. water to water vapour.

(c) LIQUEFACTION or CONDENSATION: Conversion of VAPOUR (or gas) into a LIQUID on cooling e.g. water vapour to water.

(d) SOLIDIFICATION OR FREEZING: Conversion of a LIQUID into a SOLID e.g. water to ice.

(e) SUBLIMATION: Conversion of a SOLID directly in GASEOUS (vapour) state and on cooling directly back to SOLID e.g. Naphthalene sublimes at room temperature.

Question: 10. Draw a labelled schematic diagram representing the terms – a] to e]

involved in the inter-conversion of matter-

a] Melting

b] Vaporisation

c] Liquefaction or condensation

d] Solidification or freezing

e] Sublimation

Answer: Draw a labelled schematic diagram representing the terms (a) to (e) involved in the inter-conversion of matter:

a] Melting

b] Vaporisation

c] Liquefaction or condensation

d] Solidification or freezing

e] Sublimation

Question: 11. With reference to inter-conversion of matter – on the basis of kinetic theory – explain in brief the conversion of :

a] A solid into a liquid

b] A liquid into vapour [or gas]

c] Vapour [or gas] into a liquid

d] A liquid into a solid

With special reference to inter-particle space and inter-particle attraction at the different stages of conversion.

Answer: i) Solid into liquid

Question: 12. On the basis of kinetic theory explain why, ammonium chloride sublimes and goes from solid state directly into vapour state.

Answer: Ammonium chloride (NH₄Cl) sublimes and goes from solid state to directly into a vapour state, because of the low interparticle force of attraction.

Particles of ammonium chloride (NH₄Cl) at lower temperatures gain enough energy that requires to overcome the force of attraction between the particles and ammonium chloride (NH₄Cl) gets converted directly into vapour space.

Question: 13. State the ‘law of conservation of mass’. State the main points of Landolt’s experiment for experimental evidence of the law.

Answer: Law of conservation of mass states that in any chemical reaction, the initial weight of reactants is equal to the final weight of the products. In other words, Mass can neither be created nor destroyed during a chemical reaction but it only changes from one form into another.

—: End of Matter Class-8 Dalal Simplified ICSE Chemistry Solutions Chapter-3 :—

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