MATTER - Questions & Answers
EXERCISEIntroduction
1. Explain the meaning of the term 'matter'.
Matter is defined as anything that occupies space, has mass, and can be perceived by the senses. For example, both living and non-living things are considered matter.
2. Matter in any state is composed of small particles - molecules, atoms or ions. Differentiate the terms above in italics.
Atoms: The smallest particle of an element which can take part in a chemical reaction and may or may not exist independently. Molecules: The smallest particle of a substance (element or compound) that can exist independently and retains the characteristics of that substance. Ions: Atoms or groups of atoms that carry a resultant positive or negative charge due to the loss or gain of electrons.
3. Differentiate between the two characteristics of matter - 'mass' & 'weight'.
Mass: Represents the actual quantity of matter contained in a body. It remains constant regardless of location. Weight: Represents the gravitational pull exerted by the Earth (or another celestial body) on that matter. It can change depending on the strength of gravity.
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.
a] Gases b] Solids c] Solids d] Gases e] Gases
Kinetic molecular theory
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.
a] Inter-particle space: The particles in matter are arranged such that they have spaces between them.
b] Inter-particle attraction: All particles attract each other with a force that is maximum when particles are close and minimum when they are far apart.
c] Energy possessed: Particles are in continuous motion and therefore possess kinetic energy. Application of heat increases this kinetic energy.
6. State in which of the following examples i.e. a 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.
a] A light gas
b] A piece of wood
c] A light gas
Comparative study - solids, liquids & gases
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.
In solids, the movement of atoms is only about their own fixed positions. This is because the inter-particle attraction is very strong and the inter-particle space is minimum, which holds the particles tightly in a rigid structure.
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.
1. Gases have no definite shape. Gases have no definite volume. Gases have the least density compared to solids and liquids. Gases are highly compressible. Gases diffuse very easily and rapidly.
Change of state of matter - interconversion
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
Inter-conversion of matter is the process by which matter changes from one state to another and back to its original state, usually brought about by changes in temperature or pressure.
a] Melting: Conversion of a solid into a liquid on heating (e.g., ice to water).
b] Vaporisation: Conversion of a liquid into vapour (or gas) on heating (e.g., water to steam).
c] Liquefaction: Conversion of vapour (or gas) into a liquid (e.g., water vapour to water).
d] Solidification: Conversion of a liquid into a solid (e.g., water to ice).
e] Sublimation: Process where a solid changes directly into a gaseous state (and vice versa) without passing through the liquid state (e.g., naphthalene).
10. Draw a labelled schematic diagram representing the terms - a] to e] involved in the inter-conversion of matter.
[Note: This is a description of the diagram found on page 4] A triangle is formed with three states: SOLID, LIQUID, and GAS. The arrow from SOLID to LIQUID is labeled MELTING. The arrow from LIQUID to SOLID is labeled SOLIDIFICATION (Freezing). The arrow from LIQUID to GAS is labeled VAPORISATION. The arrow from GAS to LIQUID is labeled LIQUEFACTION (Condensation). A double-headed arrow between SOLID and GAS is labeled SUBLIMATION.
Change of state of matter - kinetic theory
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 & inter-particle attraction at the different stages of conversion.
a] Solid to Liquid (Melting): On heating, particles gain energy. The inter-particle space increases and the force of attraction decreases until particles become free to move.
b] Liquid to Vapour (Vaporisation): On heating, particles gain more energy. The inter-particle space increases significantly and the attraction becomes negligible.
c] Vapour to Liquid (Liquefaction): On cooling, particles lose energy and slow down. The inter-particle space decreases greatly and the attraction increases.
d] Liquid to Solid (Solidification): On cooling, particles lose energy and their motion slows down. The inter-particle space decreases and attraction increases until they are locked in a fixed position.
12. On the basis of kinetic theory explain why, ammonium chloride sublimes and goes from solid state directly into vapour state.
Ammonium chloride is a sublimable solid that has very low forces of attraction between its particles. On heating, the particles gain enough energy to completely overcome the inter-particle attraction and break free from the solid surface directly into the vapour state.
Law of conservation of mass
13. State the 'law of conservation of mass'. State the main points of Landolt's experiment for experimental evidence of the law. State the limitations of the law.
Law: Matter is neither created nor destroyed during a chemical reaction; the total mass of reactants is equal to the total mass of products.
Landolt's Experiment:
Solutions of Sodium chloride and Silver nitrate were placed in separate limbs of an 'H'-shaped tube.
The tube was sealed and weighed.
The solutions were mixed by shaking to form a white precipitate (Silver chloride).
The tube was weighed again, and the mass remained unchanged.
Limitations: During a chemical reaction, some mass may be converted into energy (heat or light). Therefore, mass and energy should be considered together for absolute accuracy.
CRITICAL THINKING OBJECTIVE TYPE QUESTIONS
Q.1 Select the correct answer from A, B, C, D & E for each statement given below:
A: Solid B: Vaporization C: Ion D: Gases E: Heat
1. An atom or group of atoms - having a resultant charge. C: Ion
2. The state of matter which has - least density & no free surfaces. D: Gases
3. In Landolt's experiment - the form in which the chemical energy stored up in the reactants - is released. E: Heat
4. The process of change of a liquid into vapour [gas] on heating. B: Vaporization
5. The state of matter, where the inter-particle attraction between particles is maximum. A: Solid
Q.2 With reference to the liquid state of matter - answer the following:
1. On heating the liquid, do the particles gain or lose energy.
The particles gain energy.
2. The heat energy supplied to the liquid is absorbed by its molecule & stored as which form of energy.
It is stored as potential energy.
3. How does the stored energy, have effect on inter-particle space.
The stored potential energy increases the inter-particle space.
4. State why the inter-particle attraction decreases to negligible.
As heat is applied, the inter-particle space increases to a point where the particles are so far apart that the force of attraction becomes negligible.
5. At what point will the particles become free and escape as gas.
At the boiling point.
Q.3 Complete the statements by filling the blanks with the correct word from the bracket.
1. In naphthalene, the inter-particle attraction is low [high/low].
2. The law of conservation of mass, is strictly valid if mass and energy [energy/volume] are considered together.
3. When inter-particle space increases, the inter-particle attractive force decreases [decreases/increases].
4. Kinetic energy of molecules in helium is very large [large/very large] compared to the kinetic energy of molecules in water.
5. Conversion of vapour [or gas] into a liquid is termed liquefaction [liquefaction/vaporization].
Q.4 Give reasons for the following:
1. Particles of matter possess energy called kinetic energy.
Particles of matter are in continuous motion, and any object in motion possesses kinetic energy.
2. Solids cannot be compressed, but gases are highly compressible.
In solids, inter-particle spaces are minimum, leaving no room for particles to move closer. In gases, inter-particle spaces are very large, allowing them to be pushed closer together.
3. Kinetic energy of molecules of gases is very large & of solids, the least.
In gases, particles are far apart with negligible attraction, allowing rapid random motion. In solids, particles are tightly packed by strong attraction, allowing only vibration about fixed positions.
4. On heating a sublimable solid, the molecules break free & escape from surface of the solid directly into vapour.
Sublimable solids have very weak inter-particle forces. Heat energy quickly overcomes these weak forces, causing particles to move directly into the gaseous state.
5. Particles of matter move more rapidly on application of heat.
Heat energy is absorbed by the particles and converted into kinetic energy, which increases their velocity and causes them to move more randomly.
Q.5 Complete the blanks with reference to interconversion of matter on basis of kinetic theory- with the word 'increases', 'decreases', 'gain', 'lose' or 'overcome' in each case.
1. During melting of solids, the inter-particle space increases.
2. During vaporization, the liquid particles gain energy.
3. During liquefaction, the particles lose energy.
4. During solidification, the inter-particle space decreases.
5. During sublimation the inter particle attraction is overcome.