1. Give reasons.
(a) Water is not used to control fires involving electrical equipment.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily whereas a piece of
1. Give reasons.
(a) Water is not used to control fires involving electrical equipment.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily whereas a piece of
Explanation:
(a) The person putting out the fire can experience an electric shock due to the excellent electrical conductivity of water.
(Parenthesis for the sake of brevity. Moreover, it has calories.
(b) Because the paper has a low ignition temperature, it burns easily on its own. Nevertheless, if a piece of paper is wrapped around an aluminium pipe, the aluminium pipe will absorb the heat and prevent the paper from getting hot enough to ignite.) The person putting out the fire can experience an electric shock due to the excellent electrical conductivity of water.
(Parenthesis for the sake of brevity. moreover, it has calories.
(c) Because the paper has a low ignition temperature, it burns easily on its own. Nevertheless, if a piece of paper is wrapped around an aluminium pipe, the aluminium pipe will absorb the heat and prevent the paper from getting hot enough to ignite.
paper wrapped around an aluminium pipe does not.
2. Explain how CO2 is able to control fires.
2. Explain how CO2 is able to control fires.
Explanation:
CO2 blankets the fire, preventing it from receiving any new air, as it is heavier than oxygen. It lowers the burning substance's temperature. It significantly aids in fire control in a variety of ways.
3. It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain.
3. It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain.
Explanation:
Burning a pile of green leaves is difficult, but dried leaves burn easily. Explain.
The water in the green leaves enhances the ignition temperature and makes burning more challenging. On the other side, since dried leaves don't have any moisture, they burn easily (having low ignition temperature).
4. Why does a goldsmith melt gold and silver in a certain zone of a flame?
4. Why does a goldsmith melt gold and silver in a certain zone of a flame?
Explanation:
Goldsmiths exploit a flame's outermost, non-luminous portion, which has the highest temperature, to melt metals like gold and silver.
5. List conditions under which combustion can take place.
5. List conditions under which combustion can take place.
Explanation:
The following factors must be present for combustion to occur: • A combustible substance must be present; and • An oxygen-containing environment must be present.
• The ignition temperature is reached.
6. Why is respiration referred to as slow combustion ?
6. Why is respiration referred to as slow combustion ?
Explanation:
Although oxidation occurs during breathing, the energy released is so slowly that we cannot detect it. As a result, it is referred to as sluggish combustion.
7. Distinguish between combustible and non-combustible substances.
7. Distinguish between combustible and non-combustible substances.
Explanation:
Combustible substances: These are the materials that burn easily, such as paper and cloth.
Non-combustible substances: These are the substances that do not burn easily, such as glass and iron.
8. Why do different materials burn at various temperatures?
8. Why do different materials burn at various temperatures?
Explanation:
Because different materials have varying ignition temperatures, they burn at various temperatures.
9. Can water be used to extinguish an electric short-circuit fire? Why ?
9. Can water be used to extinguish an electric short-circuit fire? Why ?
Explanation:
We cannot use water to put out a fire brought on by an electric short circuit since it is a conductor of electricity and can result in electric shock.
10. What does "spontaneous combustion" mean? Provide one instance of a substance that spontaneously burns.
10. What does "spontaneous combustion" mean? Provide one instance of a substance that spontaneously burns.
Explanation:
A substance spontaneously catches fire without a clearly visible external origin, as is the case with phosphorus.
11.(1) Name the type of nuclear reaction taking place in the atmosphere of Sun.
(2) Define ignition temperature.
(3) Why water should not be used to put out fire caused by burning of petrol.
11.(1) Name the type of nuclear reaction taking place in the atmosphere of Sun.
(2) Define ignition temperature.
(3) Why water should not be used to put out fire caused by burning of petrol.
Explanation:
One is nuclear fusion.
1:The ignition temperature is the lowest temperature at which a substance must be heated in order to begin burning
2.Because gasoline is lighter than water, it floats on top of the water while burning continuously. Because gasoline burns, it cannot be used to put out fires. out fires.
