A. Tick the correct answer:-

1. A 2.C 3. C 4. B 5. D

B. Differentiate between the following:-

1. Those substances burn in presence of oxygen are called a combustible substances

 example diesel.

        Those substances do not burn in presence of oxygen are called non combustible.e.g stone

2. Carbon burns in presence of sufficient oxygen to form carbon dioxide.

C+O₂--air->CO₂

       Carbon burns in presence of insufficient oxygen form carbon monoxide.

2C+O₂--->2CO

3. Soda acid on reaction gives carbon extinguisher.

         Dioxide which extinguishes fire(CO₂)

Na₂CO₃+H₂SO₄--->CO₂+H₂O+Na₂SO₄

4. Oxidation flame is called oxidize all luminous flame.

          Production flame is called reduced flame.

C. Give one word answer for each of the following:-

1. Oxidation 2. Non luminous zone 3. Combustible 4. Carbon particulate 5. Hydrocarbon

D. Match column a with column b:-

1. Combustion 2. Fire extinguisher 3. Luminous zone 4. Innermost zone 5. Global warming

E. Give two examples for each of the following:-

1. Diesel,petrol 2. Diwali bomb, atom bomb 3. CaCO₃/Hcl and Na₂CO₃/Hcl 4. Petrol, diesel

F. Give reasons for each of the following:-

1. Oxygen supports combustion. It forms a combustible mixture with other gases.

2. Ignition temperature is minimum temperature attained by a substance to burn a substance. Generally it is slightly above room temperature.

3. Rusting and digestion are called slow combustion because they take place very slowly.

C₆H₁₂O₆+O₂--digestion>CO₂+H₂O+energy

glucose.

4. Candle flame is yellow because molten wax forms are reducing mixture with air.

G. Write true or false:-

1. False 2. True 3. True 4. False 5. False

H. Circle the odd one out:-

1. Sulphur dioxide 2. Coal 3. Sand 4. Iron 5. Crude oil

I. Fill in the blanks:-

1. Oxide and hydride 2. Hydrogen 3. Ionic compound 4. Four 5. Dust and smoke

J. Short answer questions:-

1. Combustion is a process in which oxygen combines with other substance.

2. Those substances which undergo chemical change are called combustion. Fuels undergoes combustion.

          None fuel substances do not undergo combustion example marble.

3. Fire extinguishers extinguishes fire. There are four types  fire extinguisher.

4. Burning part of a fuel is called flame. Yellow flame is a reduced flame,blue flame is a oxidised flame.

5. Those substances burn to produce energy are called fuel example coal ,oxygen

  K. Long answer questions:-

1. Oxidation means addition of oxygen. Combustion is a type of oxidation 

Reactions

2Zn+O₂--->2ZnO

O₂+H₂-elctricity-->2Fe₂O₃

4Fe+3O₂--->2Fe₂O₃ 

2Mn+O₂---->2MnO

Condition necessary for combustion

1. Supply of oxygen

2. Presence of an ignition temperature above room temperature

3. Presence of combustible substance 

2. Types of combustion are-

(i). Rapid combustion-It takes place very quickly.

C₄H₁₀+O₂---->CO₂+H₂O 

(ii).  Slow combustion- It takes place slow 

C₆H₁₂O₆+6O₂--->6CO₂+6H₂O

(iii). Explosion- Burning of Diwali cracker

(iv). Spontaneous combustion- It takes place gradually 

P₄+5O₂--->2P₂O₅ 

3. When is substance burns completely in presence of substance that oxygen is called complete combustion.

C+O₂--->CO₂ 

When a substance burns in presence of insufficient supply of oxygen is called incomplete combustion.

2C+O₂---->2CO

Disadvantages of incomplete combustion 

(i). Carbon produces poisonous carbon monoxide gas.

(ii). NTPC produces Carbon dust and smoke into the atmosphere which causes breathing problem

Precautions to be taken

(i). Supply of oxygen should be sufficient

(ii). Gas stove, kerosene stove should be cleaned occasionally 

4.(i) To cut off supply of oxygen

(ii) To spray sufficient water over flame to reduce ignition temperature

(iii) To remove the burning substance.

5. (i) Blue zone is a zone where CO burns with a blue flame carbon monoxide.

(ii) Dark zone and luminous zone are reducing zone due to insufficient supply of oxygen.

(iii) The outer zone is luminous zone because there flame burns with atmospheric oxygen.

Draw the figure of zones of candle flame in this place by yourself

6. Classification of fuels

State -solid fuel -coal 

Liquid fuel-kerosene oil 

Gaseous fuel- hydrogen gas 

Source as primary fuel- coal 

Secondary fuel- coke

Regeneration:

Renewable source- wind

Non renewable source- gasoline 

7. Harmful gases are produced by burning fuels

Sulphur dioxide- Gasoline burns in presence of oxygen to produce Sulphur dioxide

Nitrogen oxides- Coal burns to produce various oxides of nitrogen 

Carbon monoxide- Carbon burns in presence of insufficient air to produce carbon monoxide 

Carbon dioxide- Carbon burns in sufficient air to produce carbon dioxide