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Important questions on Combustion

A chemical process in which a substance reacts with oxygen to give off heat is called _____________.

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A chemical process in which a substance reacts with oxygen to give off heat is called Combustion.

The substance which undergoes combustion is called ________.

A

fuel

B

non-inflammable

C

combustible

D

Both &

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The substance that undergoes combustion is said to be combustible. It is also called a fuel. During combustion, a chemical change occurs. The substance reacts with oxygen and releases heat. Hence, the substance acts as fuel. A combustible substance is one which readily undergoes combustion.

A physical process in which a substance reacts with oxygen to give off heat is called combustion.

A

True

B

False

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It's not a physical process rather it's a chemical process.
Hence, the given statement is "False". 

It is advisable to keep stirring heap of wastes while burning them. Write down two disadvantages, of partial combustion. 

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Partial combustion pollutes the air by giving excess of smoke, soot, carbon monoxide an carbon dioxide. 

In photosynthesis in plants, and react in presence of light and chlorophyll to give carbohydrate and oxygen. When the carbohydrate is burnt in air, the gases produced are:

A

B

C

D

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The carbohydrate is glucose. The combustion of glucose is as follows:

Combustion occurs when any organic material is reacted (burned) in the presence of oxygen to give off the products of carbon dioxide and water and energy.This is simply the process of metabolism.

It is advisable to keep stirring heap of wastes while burning them 
How does the stirring help the combustion? Explain

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Sufficient oxygen is made available which increases the rate of combustion

Which of the following is not true about combustion?

A

In case of chimney when air does not enters from below, the candle burns freely

B

In case of chimney candle burns freely when air enters from below the chimney

C

In case of chimney when air does not enters from below, the flame flickers and produces smoke

D

In the absence of air candles flame flickers but does not goes off

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The statement (A)  is not true about combustion.
In case of chimney when air enters from below, the candle burns freely. If their is no supply of air from below, the candle cannot burn freely. This is because air supply is essential for combustion.

Write down any two examples of combustible.

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Petrol and coal. 

When magnesium ribbon burnt it produce:

A

Magnesium hydroxide

B

Magnesium oxide

C

Magnesium chloride

D

Magnesium sulphate

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When magnesium ribbon burns, it reacts with the oxygen present in the air and form a powdery ash called magnesium oxide.

.

Hence option B is correct.

Explain Combustion reaction with example.

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Combustion reaction: Carbon compounds burns in oxygen to produce carbon dioxide along with release of large amount of heat and light.

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