Combustion and Flame Test

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Combustion and Flame Test - 29

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Question 1
1 / -0

Which chemical substance is emitted in car exhaust and is a cause of acid rain?

A
Nitrogen oxides

B
Lead

C
Carbon dioxide

D
DDT

E
Nitrates

Solution

Nitrogen Oxides are emitted in car exhaust and are a cause of acid rain.
Fuels, such as coal and petroleum have some amount of sulphur and nitrogen. On combustion, such fuels form oxides of sulphur and nitrogen which is an environmental hazard and cause of acid rain.
Option $$A$$ is correct.
Question 2
1 / -0

How water helps in extinguishing fire?

A
Water cools the combustible material so that its temperature is brought below the ignition temperature.

B
Water heats the combustible material so that its temperature is brought below the ignition temperature.

C
Water cools the combustible material so that its temperature is brought above the ignition temperature.

D
None of these

Solution

Water cools the combustible material so that its temperature is brought below the ignition temperature. This prevents the fire from spreading. Water vapour also surrounded the combustible material helping in cutting off the supply of air. So, the fire is extinguished.

Hence, correct option is $$A$$.
Question 3
1 / -0

During burning of candle, different zones of combustion in the flame are listed below:-
a) Outermost zone
b) Innermost zone
c) Middle zone

The correct order of temperature of zones is :

A
$$A>B>C$$

B
$$C>B>A$$

C
$$B>C>A$$

D
$$A>C>B$$
Solution
The flame consist of three zones:
The outermost zone is the hottest among the 3 and is blue in colour.
The middle zone is moderately hot and is yellow in colour.
The innermost zone is the least hot and black in colour.
Question 4
1 / -0

What reactant must be present for a reaction to be classified as combustion?

A
$${Cl}_{2}$$

B
$${CH}_{4}$$

C
$${O}_{2}$$

D
$${CO}$$

Solution

Three things are required in proper combination before ignition and combustion can take place---heat, oxygen, and fuel. oxygen helps as an oxidizer in the oxidizing hydrocarbons to form $$CO_2, H_2O $$ and heat.
Question 5
1 / -0

Which kind of material is extinguished by water on burning?

A
Wood

B
Paper

C
Petrol

D
Both a and b

Solution

The most common fire extinguisher is water, but water works only when things like wood and paper are on fire.
Water is not useful in extinguishing fire due to petrol. Petrol is inflammable material. In such cases, carbon dioxide is used instead of water because it is heavier than oxygen and can cover fire like a blanket and cut off the oxygen supply to the fire and hence fire can be controlled.
Hence, option $$D$$ is correct.
Question 6
1 / -0
1. What is geothermal energy ?
A
Ocean thermal energy

B
Interior heat of the earth.

C
Energy obtained from the heat of hot dry rocks

D
None of these

Solution

Geothermal energy is the energy obtained from the heat of hot dry rocks in the earth's crust, geysers, hot springs, etc.
Question 7
1 / -0

$$I$$. The most significant way in which humans are exposed to mercury is through drinking water.
$$II$$. A great deal of mercury enters the atmosphere because of coal-burning power plants.

A
Statement $$I$$ is true, Statement $$II$$ is true

B
Statement $$I$$ is true, Statement $$II$$ is false

C
Statement $$I$$ is false, Statement $$II$$ is true

D
Statement $$I$$ is false, Statement $$II$$ is false

E
Statement $$I$$ is true, Statement $$II$$ is true and is a correct explanation of the phenomena described in $$I$$

Solution

The correct answer is A.
Indeed, the most significant way in which humans are exposed to mercury is through drinking water and a great deal of mercury enters the atmosphere because of coal-burning power plants.
Question 8
1 / -0

Fire extinguishers containing $$CO_2$$ are the best extinguishers for fires involving electrical equipment:

A
because $$CO_2$$ being heavier than oxygen covers the fire like a blanket.

B
because $$CO_2$$ being heavier than oxygen increases fire.

C
because $$CO_2$$ being lighter than oxygen covers the fire like a blanket.

D
None of these

Solution

For fires involving electrical equipment and inflammable material like petrol, carbon dioxide is the best extinguisher. Carbon dioxide being heavier than oxygen covers the fire like a blanket. Since the contact between the fuel/inflammable material and oxygen is cut off, the fire is extinguished.
Question 9
1 / -0

The unit of calorific value is:

A
kJ/kg

B
kg/kJ

C
mg/kJ

D
g/kJ

Solution

The unit of calorific value is kJ/kg or J/kg. The amount of heat energy produced on complete combustion of 1 kg of a fuel is called its calorific value
Question 10
1 / -0

How carbon dioxide is stored in the house to extinguish fire?

A
It can store in the bottles

B
It can store in the cylinders under high pressure

C
It can store in canes

D
It can not store in any form

Solution

Carbon dioxide is a gas that can be store in cylinders under high pressure like LPG. When it is released from the cylinder, carbon dioxide expands enormously in volume and cools down. So, it does not only forms a blanket around the fire but also brings down the temperature of the fuel.

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Re-Attempt Weekly Quiz Competition

Combustion and Flame Test - 29

Result

Combustion and Flame Test - 29

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SHARING IS CARING

Question 1

Nitrogen oxides

Lead

Carbon dioxide

DDT

Nitrates

Solution

Question 2

Water cools the combustible material so that its temperature is brought below the ignition temperature.

Water heats the combustible material so that its temperature is brought below the ignition temperature.

Water cools the combustible material so that its temperature is brought above the ignition temperature.

None of these

Solution

Question 3

$$A>B>C$$

$$C>B>A$$

$$B>C>A$$

$$A>C>B$$

Solution

Question 4

$${Cl}_{2}$$

$${CH}_{4}$$

$${O}_{2}$$

$${CO}$$

Solution

Question 5

Wood

Paper

Petrol

Both a and b

Solution

Question 6

Ocean thermal energy

Interior heat of the earth.

Energy obtained from the heat of hot dry rocks

None of these

Solution

Question 7

Statement $$I$$ is true, Statement $$II$$ is true

Statement $$I$$ is true, Statement $$II$$ is false

Statement $$I$$ is false, Statement $$II$$ is true

Statement $$I$$ is false, Statement $$II$$ is false

Statement $$I$$ is true, Statement $$II$$ is true and is a correct explanation of the phenomena described in $$I$$

Solution

Question 8

because $$CO_2$$ being heavier than oxygen covers the fire like a blanket.

because $$CO_2$$ being heavier than oxygen increases fire.

because $$CO_2$$ being lighter than oxygen covers the fire like a blanket.

None of these

Solution

Question 9

kJ/kg

kg/kJ

mg/kJ

g/kJ

Solution

Question 10

It can store in the bottles

It can store in the cylinders under high pressure

It can store in canes

It can not store in any form

Solution

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