Which one of the following has the highest calorific value?

On placing an inverted tumbler over a burning candle. the flame extinguishes after sometime. This is because of non-availability of

The substance expected to have the highest ignition temperature out of the following is

Coal burns with

Shyam was cooking potato curry on a chulha. To his surprise. he observed that the copper vessel was getting blackened from outside. It may be due to

Fuel must be heated to its before _____________it starts burning

When the clothes of a person catch _______________the person is covered with a ___________to extinguish fire.

Wood paper and CNG are _____________substances

The type of combustion in which any substance starts to burn on its own is called_________________combustion.

________________is essential for combustion.

Air is necessary for combustion

Calorific value of wood is higher than that of coal.

Alcohol, CNG and LPG are inflammable substances.

The substances which vaporise during buming give flame.

The fuel can be in solid, liquid or in gaseous form.

Name the substance which gives heat and light after combustion.

Two glass jars A and B are filled with carbon dioxide and oxygen gases respectively. In each jar, a lighted candle is placed simultaneously. In which jar, will the candle remain lighted for a longer time and why?

How heat is produced in our body?

Which is better, LPG or wood. What is the colour of LPG flame during complete combustion.

Which type of substances produce flame? Does charcoal burn with flame?

List conditions under which combustion can take place.

Give reasons.
(a) Water is not used to control fires involving electrical equipments.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily, whereas a piece of paper wrapped around an aluminium pipe does not.

Explain how CO₂ is able to control fires.

In an experiment 4.5 kg of a fuel was completely burnt. The heat produced was measured to be 180,000 kJ. Calculate the calorific value of the fuel.

In severe cold weather, Mohan's family burnt wood in the room during the night keeping the windows close. After sometime, they felt suffocation. Mohan immediately opened the windows and get relief.
(a) What did actually happen?
(b) What values are associated with Mohan?

'Charcoal is a better fuel than wood'. Explain.

What are the three essential requirements to produce fire? How fire extinguisher is useful for controlling the fire?