Combustion and Flame Test

Result

Combustion and Flame Test - 6

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Weekly Quiz Competition

Question 1

1 / -0

Which of the following represents the correct increasing order of calorific value of the given fuels?

Hydrogen < LPG < Biogas < Cow dung cake < coal

Cow dung cake < Biogas < LPG < Coal < Hydrogen

Cow dung cake < Coal < Biogas < LPG < Hydrogen

Hydrogen < Cow dung cake < LPG < Biogas < Coal

Solution

Fuel	Calorific value (kJ/kg)
Cow dung cake	6,000 - 8,000
Coal	25,000 - 33,000
Biogas	35,000 - 40,000
LPG	55,000
Hydrogen	1,50,000

Question 2
1 / -0

Liquids and gaseous fuels have more advantages over solid fuels. Some of the advantages are

(i) Calorific value of liquid and gaseous fuels is higher than the solid fuels.

(ii) Liquids and gaseous fuels have higher ignition temperatures than the solid fuels.

(iii) Liquids and gaseous fuels are easier to store since solid fuels occupy lot of space.

(iv) Liquids and gaseous fuels burn completely, leaving no residue.

The correct advantages are

A
(i), (ii) and (iii)

B
(i), (iii) and (iv)

C
(ii), (iii) and (iv)

D
(i), (ii) and (iv).
Question 3
1 / -0

Which of the following statements are true?

I. Yellow flames are ideal for heating.

II. The substances which vaporise during burning give flames.

III. Luminous zone contains unburnt carbon particles.

IV. The non-luminous zone has highest temperature.

A
I, II and III

B
I, II and IV

C
II, III and IV

D
I, III and IV

Solution

Blue flame is much hotter than yellow flame. Yellow flame is not hot enough and it will leave blackish ring at the bottom of the substance on heating.
Question 4
1 / -0

Calorific values of some fuels are given:

Fuel Calorific value (kJ/kg)

Coal 25000-33000

Diesel 45000

LPG 55000

CNG 50000

On the basis of this data, find out the correct order of efficiency of fuels.

A
LPG > CNG > Diesel > Coal

B
Coal > Diesel > LPG > CNG

C
Diesel > CNG > Coal > LPG

D
CNG > LPG > Diesel > Coal

Solution

Higher the calorific value, higher is the fuel efficiency.
Question 5
1 / -0

Mark the correct statements) among the following.

I. Water is a very good fire extinguisher as it cools down the fuels such as wood below its ignition temperature.

II. Water is a very good fire extinguisher for burning oils and electrical equipment?

III. Sand and soil may act as a good fire extinguisher for burning oils.

A
I only

B
II only

C
III only

D
I and III only

Solution

Water works as a fire extinguisher by taking out the heat from the fire. It is never used in laboratories and electrical stores and in case of burning of oils because it will worsen the fire. Only the fire of paper, wood, or other ordinary materials can be extinguished by water. Sand can be used in laboratories fire, electrical fire and in burning of oils as it cuts off the oxygen supply.
Question 6
1 / -0

Different methods of extinguishing a fire involve the following :

I. Removing the combustible substance.

II. Cooling the substance to a temperature below its ignition temperature.

III. Cutting off the supply of air.

Which of the following statements is correct?

A
Method I is suitable in case of a building on fire.

B
Method II involves water which works when wood or paper are on fire.

C
Method III involves carbon dioxide gas which is lighter than oxygen and forms a blanket around the air.

D
All of these

Solution

Method I is not possible in case of a building on fire as the entire building is the combustible substance. Method III involves carbon dioxide which is heavier than oxygen and forms a blanket around the fire.
Question 7
1 / -0

Directions For Questions

Natural resources are classified as:

P. Exhaustible

Q. Inexhaustible

Some natural resources are

(i) Petrol, diesel

(ii) Coal, petroleum

(iii) Air, water

(iv) Cow dung cakes, sunlight

(v) Forests, minerals

...view full instructions

Which of the following represents the correct match?

A

P-(iii), (iv); Q-(i), (ii), (v)

B

P-(i), (ii), (v); Q-(iii), (iv)

C

P-(ii), (v); Q-(i), (iii), (iv)

D
None of these is a correct match.

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Fuel	Calorific value (kJ/kg)
Coal	25000-33000
Diesel	45000
LPG	55000
CNG	50000

Combustion and Flame Test - 6

Result

Combustion and Flame Test - 6

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Question 1

Hydrogen < LPG < Biogas < Cow dung cake < coal

Cow dung cake < Biogas < LPG < Coal < Hydrogen

Cow dung cake < Coal < Biogas < LPG < Hydrogen

Hydrogen < Cow dung cake < LPG < Biogas < Coal

Solution

Question 2

(i), (ii) and (iii)

(i), (iii) and (iv)

(ii), (iii) and (iv)

(i), (ii) and (iv).

Question 3

I, II and III

I, II and IV

II, III and IV

I, III and IV

Solution

Question 4

LPG > CNG > Diesel > Coal

Coal > Diesel > LPG > CNG

Diesel > CNG > Coal > LPG

CNG > LPG > Diesel > Coal

Solution

Question 5

I only

II only

III only

I and III only

Solution

Question 6

Method I is suitable in case of a building on fire.

Method II involves water which works when wood or paper are on fire.

Method III involves carbon dioxide gas which is lighter than oxygen and forms a blanket around the air.

All of these

Solution

Question 7

P-(iii), (iv); Q-(i), (ii), (v)

P-(i), (ii), (v); Q-(iii), (iv)

P-(ii), (v); Q-(i), (iii), (iv)

None of these is a correct match.

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