Question

IV. True or False
State whether the given statements are true or false.
1. Automobiles run only by using petrol.
2. CNG means ‘Connecting Neutral Gas’.
3. Coal burns with a flame.
4. Magnesium burns to produce magnesium oxide.
5. Combustion is a physical process.
6. The substance that undergoes combustion is said to be combustible.
7. Fuel may be solid, liquid or gas.
8. Wood is combustible.
9. A matchstick only contains white phosphorus.
10. Kerosene is an example of solid fuel.
11. For combustion, a substance must attain its ignition temperature.
12. The ignition temperature of phosphorus is 25°C.
13. LPG is an example of inflammable substances.
14. Water is a bad conductor of electricity.
15. Fuel, water and heat are three essential requirements for combustion.
16. The most common fire extinguisher is water.
17. Oxygen is heavier than C02.
18. The middle zone of a flame has yellow colour.
19. The calorific value of hydrogen is 1,50,000 kJ/kg.
20. Increase in nitrogen gas in atmosphere has led to ‘global warming’.

Answer 1

Answer:

1.false.Automobiles can run also by diesel.

2.false.CNG means Compressed Natural Gas.

3. True.

4.True.

5.True.

6.True.

7.True.

8.True.

9.False. Because matchstick contains red phosphorus,sulphur,potassium clorants etc.

10.False.Kerosene is a liquid fuel.

11.True.

12.False.Ignition temperature of phosphorus is 34 degree celcius.

13.False.LPG is a flammable substance.

14.False.water is good conductor of electricity.

15.False.Three requirements for combustion are heat,fuel and oxygen.

16.True.

17.False.CO2 is heavier than O2.

18.True.

19.True.

20.False.Increase in nitrogen gas not leads to global warming, increase of CO2 leads to global warming.