Fuels, Combustion and Flame Worksheet-2

Fuels, Combustion and Flame Worksheet-2

1. The inflammable substances are

(a) Hydrogen                                 (b) Phosphorus

(c) Water                                        (d) Coke

2. Why doesn't a matchstick burn by itself, even-though it is a combustible substance?

(a) It gets ignited due to the heat of friction.

(b) A combustible substance cannot catch fire below its ignition temperature.

(c) A combustible substance can catch fire below its ignition temperature.

3. A flame always points upwards because

(a) Gases produced in flame are cold

(b) Gases produced in flame are hot

(c) Hot gases are lighter and hence rise up

4. Carbon dioxide is an excellent fire extinguisher as

(a) It forms a blanket around fire

(b) It brings down the temperature of the fuel

(c) Both It forms a blanket around fire & It brings down the temperature of the fuel

(d) None of these

5. Methane burns in air to form:

(a) CO₂ + H₂O                               (b) CO₂ + H₂

(c) CO + O₂                                    (d) CO₂ + O₂ + heat

6. The combustion of Hydrocarbon gives Carbon Dioxide and water as the major products. Combustion is a ____ reaction accompanied by heat and light.

(a) Reduction                                (b) Redox

(c) substitution                             (d) Oxidation

7. Different substances have different temperatures at which they can start burning. Which of the following is a non-combustible substance?

(a) Coke             (b) Diamond     (c) Coal              (d) Wood

8. The lowest temperature at which a substance starts burning is called:

(a) minimum temperature        (b) maximum temperature

(c) boiling temperature              (d) ignition temperature

9. A burning substance will be ____ if the temperature falls below its ignition temperature.

(a) Extinguished                           (b) burning brightly

(c) burning dimly                         (d) burning with smoke

10. The conditions necessary for combustion are:

(a) presence of combustible substance

(b) presence of supporter of combustion

(c) attainment of ignition temperature

(d) all of these

Answer Key:

(1)-(a,b); (2)-(a,b); (3)-(b,c); (4)-(a,b); (5)-(a); (6)-(d); (7)-(b); (8)-(d); (9)-(a); (10)-(d)