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Important Questions: Combustion And Flame


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20 Questions MCQ Test Science Class 8 | Important Questions: Combustion And Flame

Important Questions: Combustion And Flame for Class 8 2022 is part of Science Class 8 preparation. The Important Questions: Combustion And Flame questions and answers have been prepared according to the Class 8 exam syllabus.The Important Questions: Combustion And Flame MCQs are made for Class 8 2022 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Important Questions: Combustion And Flame below.
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Important Questions: Combustion And Flame - Question 1

The substances which give heat and light after combustion are called

Detailed Solution for Important Questions: Combustion And Flame - Question 1

The substance which undergoes combustion is said to be combustible. It is called fuel. If a magnesium ribbon is heated,it starts burning. When a magnesium ribbon burns, it combines with the oxygen of air to form magnesium oxide, and liberates heat and light.

Important Questions: Combustion And Flame - Question 2

Like fuels the sun also provides heat and light. The process taking place in the sun is called

Important Questions: Combustion And Flame - Question 3

Coal burns with

Detailed Solution for Important Questions: Combustion And Flame - Question 3 Charcoal is a solid fuel which does not vapouriseon heating. So, charcoal does not burn by producing a flame. It only glows on combustion.
Important Questions: Combustion And Flame - Question 4

Burning of charcoal in a closed room will produce

Detailed Solution for Important Questions: Combustion And Flame - Question 4 Incomplete combustion of coal gives carbon monoxide gas. It is a very poisonous gas. It is dangerous to burn coal in a closed room. The carbon monoxide gas produced can kill persons sleeping in that room. So we should not sleep in a closed room with burning coal fire in it.
Important Questions: Combustion And Flame - Question 5

The substances which have very low ignition temperature will

Important Questions: Combustion And Flame - Question 6

CNG and LPG are the examples of

Important Questions: Combustion And Flame - Question 7

Ignition temperature is

Important Questions: Combustion And Flame - Question 8

Combustion is a

Important Questions: Combustion And Flame - Question 9

The products of combustion are

Detailed Solution for Important Questions: Combustion And Flame - Question 9

A is the correct option.A combustion reaction is a reaction in which a substance reacts with oxygen gas, releasing energy in the form of light and heat. Combustion reactions must involve O2 as one reactant. The products of combustion are carbon dioxide and water.

Important Questions: Combustion And Flame - Question 10

There are following zones of a flame

Detailed Solution for Important Questions: Combustion And Flame - Question 10

It is because there are only three zones in a flame i.e. dark zone, non luminous zone, luminous zone

Important Questions: Combustion And Flame - Question 11

Coal is a fuel which can produce flame.

Important Questions: Combustion And Flame - Question 12

The innermost part of the flame has very least temperature.

Important Questions: Combustion And Flame - Question 13

CNG stands for Common Natural Gas.

Detailed Solution for Important Questions: Combustion And Flame - Question 13

B is the correct option.Compressed natural gas (CNG) (methane stored at high pressure) is a fuel that can be used in place of gasoline, diesel fuel and liquefied petroleum gas (LPG).

Important Questions: Combustion And Flame - Question 14

Carbon monoxide is a poisonous gas.

Important Questions: Combustion And Flame - Question 15

Acid rain is very useful for the crops, buildings and the soil. 

Important Questions: Combustion And Flame - Question 16

Oxygen is required for the burning of any substance.

Important Questions: Combustion And Flame - Question 17

The lowest temperature at which any substance catches fire is called ignition temperature.

Important Questions: Combustion And Flame - Question 18

 Oxygen is the product of any burning process.

Detailed Solution for Important Questions: Combustion And Flame - Question 18

Carbon dioxide is the most common gas produced by burning.

Important Questions: Combustion And Flame - Question 19

C.N.G. and L.P.G. burn with sooty flame

Detailed Solution for Important Questions: Combustion And Flame - Question 19

They burn produced blue flame ,so they burn with a sooty flame.The blue is called "chemoluminescence". It's the light produced directly by the combustion reaction, and will therefore be present during most hydrocarbon fires. The yellow and orange (which provide most of the light from the actual fire) come from a more interesting source. When hydrocarbons burn without sufficient oxygen mixed in, they burn incompletely. This reaction produces tiny particles of solid carbon, which we generally refer to as 'soot'. The flame is full of this finely dispersed carbon, which gets heated by the combustion. A typical wood fire produces flames anywhere from 1000 K to 2000 K. At that temperature, the particles glow, giving off orange to yellow light. Those tiny bits of superhot carbon is what causes most of the light we see from fires.

Gas burners are generally designed to mix plenty of air in with the gas before it burns. so that incomplete combustion doesn't happen, soot doesn't get produced, and so all you see is the blue from the combustion. But if you block some of the air from getting into the burners, you'll find that gas flames burn just as yellow as wood.

Important Questions: Combustion And Flame - Question 20

All the fuels burn with blue flame.

Detailed Solution for Important Questions: Combustion And Flame - Question 20

The correct option is B.
All the gases which undergo combustion produce flame. But only those solids and liquid fuels which vaporise on being heated,burn with the flame

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