Combustion and Flame Test

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Combustion and Flame Test - 30

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Weekly Quiz Competition

Question 1
1 / -0

A thin paper cup filled with water does not catch fire when placed over a flame. This is because:

A
the water cuts off oxygen supply to the paper cup

B
water is an excellent conductor of heat

C
the paper cup does not reach to ignition temperature

D
paper is a poor conductor of heat

Solution

On heating a paper bowl containing water, the water present in it absorbs the heat coming from the burning source and thus prevents the paper from reaching its ignition point. Hence, it does not burn. The water in the bowl becomes hot. This is due to the absorption of heat by the water.
Hence, option $$C$$ is correct.
Question 2
1 / -0

The cooking gas burns rapidly and produces heat and light. Such combustion is called _________.

A
rapid combustion

B
incomplete combustion

C
regular combustion

D
none of these

Solution

The cooking gas burns rapidly and produces heat and light. Such combustion is called rapid combustion. The burning of the matchstick is also an example of rapid combustion.
Question 3
1 / -0

Which of the following example represents spontaneous combustion?

A
Burning of matchstick.

B
Burning of cooking gas.

C
Ignition of a cracker.

D
Phosphorus burns in air at room temperature
Question 4
1 / -0

Which of the following examples represents explosion?

A
Burning of matchstick

B
Burning of cooking gas

C
Ignition of a cracker

D
Burning of phosphorus in air at room temperature

Solution

Ignition of a cracker is an example of explosion. When a cracker is ignited, large amount of heat, light, gas and sound are released due to a sudden reaction.

The burning of phosphorus in air at room temperature is an example of spontaneous combustion.

Burning of matchstick and burning of cooking gas are examples of rapid combustion.
Question 5
1 / -0

If you watch a burning candle carefully, you will find different colurs in the flame. Which is the hottest part of the candle flame?

A
The middle orange part

B
The middle, yellow part

C
The outermost portion that is blue

D
The innermost black zone

Solution

The outermost portion is blue.
The hottest part of the candle flame is the blue part, Which is at about $$1400^oC$$ i.e., the outermost portion, where the flame has the most oxygen for burning due to which complete combustion takes place.
Question 6
1 / -0

Explosion of crackers takes place due to application of _________ on them.

A
temperature

B
pressure

C
heat

D
none of these

Solution

An explosion can take place when pressure is applied on the cracker. When a cracker is ignited, a large amount of heat, light, gas, and sound are released due to a sudden reaction that creates pressure inside.
It represents an explosion.
Question 7
1 / -0

When fuel is added to the exhaust (burnt) gases in a jet engine combustion takes place. Some facts are mentioned here about this combustion. Pick the false one?

A
It increases the intake of oxygen from the air

B
It reduces fuel consumption

C
It gives additional thrust

D
It is known as 'after burning'

Solution

When fuel is added to exhaust gases in a jet, engine combustion takes place to release energy so that it gives additional thrust to increase efficiency of the engine.
Question 8
1 / -0

A white solid $$X$$ reacts with dil.$$HCl$$ to give colourless gas which is used in fire extinguishers. The solid $$X$$ is:

A
$$NaCl$$

B
$$CH_3COONa$$

C
$$Na_2CO_3$$

D
$$NaHCO_3$$

Solution

Sodium bicarbonate can be used for fire extinguishers purpose as it releases carbon dioxide.
The following reaction takes place:

$$ NaHC{ O }_{ 3 }(X)\ +\ HCl\ \rightarrow \ NaCl\ +\ C{ O }_{ 2 }\ +\ { H }_{ 2 }O $$

Hence the correct option is $$\text{D}$$.
Question 9
1 / -0

If butane on combustion gives carbon monoxide, find the number of $$O_ 2$$ molecules required.

A
6

B
5.5

C
4.5

D
4

Solution

Balanced reaction:

$$C_4H_{10} +\dfrac{9}{2} O_2 \rightarrow 4CO(g) +5H_2O (l)$$

Therefore number of $$O_2$$ molecules required for complete combustion of butane is $$\dfrac{9}{2}=4.5\ mol$$
Question 10
1 / -0

Gobar gas contains mainly:

A
methane

B
ethane

C
butane

D
carbon monoxide

Solution

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Combustion and Flame Test - 30

Result

Combustion and Flame Test - 30

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SHARING IS CARING

Question 1

the water cuts off oxygen supply to the paper cup

water is an excellent conductor of heat

the paper cup does not reach to ignition temperature

paper is a poor conductor of heat

Solution

Question 2

rapid combustion

incomplete combustion

regular combustion

none of these

Solution

Question 3

Burning of matchstick.

Burning of cooking gas.

Ignition of a cracker.

Phosphorus burns in air at room temperature

Question 4

Burning of matchstick

Burning of cooking gas

Ignition of a cracker

Burning of phosphorus in air at room temperature

Solution

Question 5

The middle orange part

The middle, yellow part

The outermost portion that is blue

The innermost black zone

Solution

Question 6

temperature

pressure

heat

none of these

Solution

Question 7

It increases the intake of oxygen from the air

It reduces fuel consumption

It gives additional thrust

It is known as 'after burning'

Solution

Question 8

$$NaCl$$

$$CH_3COONa$$

$$Na_2CO_3$$

$$NaHCO_3$$

Solution

Question 9

6

5.5

4.5

4

Solution

Question 10

methane

ethane

butane

carbon monoxide

Solution

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