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Ritambhara

Nov 6, 2014



Abcdefgh

Nov 30, 2013



Mangesh

Aug 18, 2015

#### Three examples of non combustible substances.



Examples of non-combustible substances are
rock,steel,water,sand etc.

Prasheek Shashikant

Nov 18, 2013

####      Why carbon dioxide gas is used to extinguished fire caused by petrol  Diesel or kerosene? Why not water?



In case of oil fires, water is not suitable for extinguishing the fire because diseal is less dense than water and will float in water. As water will spread, such the oil will spread and the fire will become mo...

Arjun R.Unnithan

Nov 12, 2013

#### I found the answer as 40000 KJ/Kg but the answer in the Learn Next NCERT Science Solution it is given as 4000KJ/Kg.When I referes to the Calculator it shown that 180000/4.5= 40000.



solution=  180000/4.5
=  1800000/4.5 as the decimal goes to N = numerator
=4000kj/kg
ok

Dhruv Tanwar

Mar 8, 2015

#### dry leaves catch fire easily but it is difficult to burn a heap of green leaves ?



Green leaves do not catch fire easily. For  any substance to burn it has to reach its ignition temperature. The Ignition temperature is the lowest temperature at which a material catches fire.
...

Sharanya

Oct 22, 2013

#### EXAMPLE OF SLOW COMBUSTION ?



celluler respiration

Mohit Dubey

Aug 23, 2015

#### why are gaseous fuels better than solid and liquid ones?



Calorific value is defined as the amount of heat energy produced on complete combustion of 1 kilogram of a fuel. When a gaseous fuel burns it gives off a great deal of energy .

And unl...

Raj Sharma

Mar 4, 2014

#### what is the equation of soda acid fire extinguisher?



2NaHCO3 + H2SO4 ⇒ Na2SO4 + 2H2O + 2CO2

Saloni somani

Nov 15, 2014

#### In olden times when we used to cook the food on chulha , we used to light the papers , dry grass or some pieces of wood. It would not catch the fire so we used to blow the air from a pipe so that it could catch fire instantly. But at the same time, we use a blow of air to extinguish the flame of a candle . So the question is how the blow of air can also create fire and can also extinct fire?



Hi saloni!
Oxygen is necessary for combustion.
Blowing out a candle makes the candle goes out. Because in candle the flame is due to burning of  vapoutized wax. When we blow the candle the va...

Ritambhara

Nov 6, 2014



Abcdefgh

Nov 30, 2013



Mangesh

Aug 18, 2015

#### Three examples of non combustible substances.



Examples of non-combustible substances are
rock,steel,water,sand etc.

Prasheek Shashikant

Nov 18, 2013

####      Why carbon dioxide gas is used to extinguished fire caused by petrol  Diesel or kerosene? Why not water?



In case of oil fires, water is not suitable for extinguishing the fire because diseal is less dense than water and will float in water. As water will spread, such the oil will spread and the fire will become mo...

Arjun R.Unnithan

Nov 12, 2013

#### I found the answer as 40000 KJ/Kg but the answer in the Learn Next NCERT Science Solution it is given as 4000KJ/Kg.When I referes to the Calculator it shown that 180000/4.5= 40000.



solution=  180000/4.5
=  1800000/4.5 as the decimal goes to N = numerator
=4000kj/kg
ok

Dhruv Tanwar

Mar 8, 2015

#### dry leaves catch fire easily but it is difficult to burn a heap of green leaves ?



Green leaves do not catch fire easily. For  any substance to burn it has to reach its ignition temperature. The Ignition temperature is the lowest temperature at which a material catches fire.
...

Sharanya

Oct 22, 2013

#### EXAMPLE OF SLOW COMBUSTION ?



celluler respiration

Mohit Dubey

Aug 23, 2015

#### why are gaseous fuels better than solid and liquid ones?



Calorific value is defined as the amount of heat energy produced on complete combustion of 1 kilogram of a fuel. When a gaseous fuel burns it gives off a great deal of energy .

And unl...

Raj Sharma

Mar 4, 2014

#### what is the equation of soda acid fire extinguisher?



2NaHCO3 + H2SO4 ⇒ Na2SO4 + 2H2O + 2CO2

Saloni somani

Nov 15, 2014

#### In olden times when we used to cook the food on chulha , we used to light the papers , dry grass or some pieces of wood. It would not catch the fire so we used to blow the air from a pipe so that it could catch fire instantly. But at the same time, we use a blow of air to extinguish the flame of a candle . So the question is how the blow of air can also create fire and can also extinct fire?



Hi saloni!
Oxygen is necessary for combustion.
Blowing out a candle makes the candle goes out. Because in candle the flame is due to burning of  vapoutized wax. When we blow the candle the va...

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