Short answer type questions,
(a) Define combustion.
(b) What is ignition temperature?
(c) Explain what will you use to put off a fire caused by electrical zadzes!
(d) List the conditions essential for combustion.
Long answer type questions.
(a) Distinguish between rapid and spontaneous combustion.
b) Describe the zones of a flame in brief.
(c) How is a flame produced when a candlewick is burnt?
(d) List the harmful effects of burning carbon-containing fuels.
(e) What causes global warming?
i Explain how does a fire extinguisher help in putting out a fire.
g) What is energy crisis? How can it be prevented?
Th) Distinguish between complete and incomplete combustion.
Answers
Answer:
(a) Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.
(b) The autoignition temperature or kindling point of a substance is the lowest temperature in which it spontaneously ignites in a normal atmosphere without an external source of ignition, such as a flame or spark. ... The ignition temperature of a substance is the least temperature at which the substance starts combustion.
(c) i don't know.
(d) Necessary factors required for a combustion reaction to take place are :
A combustible or flammable substance. For example wood, petroleum, etc.
Ignition temperature. The fuel must be at or above this 'ignition temperature'.
A gas that is a supporter of combustion (oxygen). An abundant supply of such a gas is required.
(e) RAPID COMBUSTION = When a substance bursts in a short span of time, the combustion of the substance is almost complete and a large amount of heat and light is produced. ... SPONTANEOUS COMBUSTION = In this type of combustion, a substance catches fire as soon as its temperature reaches the ignition temperature.
(f) There are three zones in flame, viz. outer zone, middle zone and inner zone. Outer Zone: This zone is blue in colour. It is the hottest part of the flame, because complete combustion takes place in this zone.
(g) Because the wick is absorbent it sucks the liquid wax into the wick and upward into the flame. Once the liquid wax gets hot enough, it then turns from a liquid into a gas. The hot gas then reacts with the oxygen from the air and is burned, creating the candle flame that we see.
(h) harmful effects of burning fuels cause following problem:
air pollution.
release carbon monoxide which leads to ozone layer depletion.
global warming.
release sulphur dioxide which cause acid. rain.
(g) i don't know.
hope you got it.
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