Combustion and flame Worksheet-2

Combustion and flame Worksheet-2

Multiple Choice Questions:

1. Water should not be used to extinguish _____.

A. Fire due to electric short circuit

B. Fire due to burning of wood

C. Fire due to burning of cotton

D. Fire due to crackers

2. When magnesium ribbon is burnt it produces ______.

A. Magnesium hydroxide           B. Magnesium oxide

C. Magnesium chloride              D. Magnesium sulphate

3. Charcoal burns in air producing-

A. CO₂                B. CO                  C. H₂                   D. O₂

4. Combustion is a reaction in which a substance reacts with-

A. Hydrogen     B. Nitrogen       C. Oxygen           D. Chlorine

5. Fuel may be-

A. Solid                                           B. Liquid

C. Gas                                              D. All of these

Head of the safety match is made from ______ and _____.

A. Bismuth trisulphide and potassium chlorite

B. Nitrous oxide and potassium chlorate

C. Antimony trisulphide and potassium chlorate

D. Oxides of nitrogen

7. Combustion is a-

A. Physical process

B. Chemical process

C. Physical process & Chemical process

D. None of these

8. Which the following is combustible?

A. Iron nail                                     B. Glass

C. Stone pieces                              D. Paper

9. The lowest temperature at which a Substance catches fire is called its-

A. Boiling point                             B. Melting point

C. Ignition temperature              D. Critical temperature

10. Which of the following has lower ignition temperature?

A. Wood                                          B. Paper

C. Vegetable oil                             D. Kerosene oil

Answer Key:

1. A

Explanation: Water should not be used over electrical fires, as it conducts electricity and can pose danger to people trying to extinguish the fire.

Turning off main power and use of fire extinguisher is recommended to extinguish electric fires.

2. B

Explanation: 2Mg + O₂ → 2MgO

Magnesium reacts with oxygen producing Magnesium oxide.

3. A

Explanation: Charcoal burns in air producing carbon dioxide and water.

4. C

Explanation: A chemical process in which a substance reacts with oxygen producing heat is called combustion.

5. D

6. C

Explanation: The head of the safety match is made from antimony trisulphide and potassium chlorate. The rubbing surface has powdered glass and a little red phosphorous.

When the matches is struck against the rubbing surface, some red phosphorous get converted into white phosphorous which reacts with the potassium chlorate in the match ignite antimony trisulphide and start the combustion.

7. B

Explanation: A substance reacts with oxygen producing carbon dioxide and water during combustion. Combustion is a chemical process.

8. D

9. C

10. D