Anil Ahlawat Solutions for Chapter: Combustion and Flame, Exercise 1: EXERCISES

A spoon is kept in contact with ice cubes for some time. Later, the same spoon was held over the flame of a small candle. The observation is shown in the figure. What do you infer from the given figure?

Which of the following statements are true?
I. Yellow flames are ideal for heating.
II. The substances which vaporise during burning give flames.
III. Luminous zone contains unburnt carbon particles.
IV. The non-luminous zone has the highest temperature.

Calorific values of some fuels are given:

On the basis of this data, find out the correct order of efficiency of fuels.

Different zones of a candle flame are marked by the letters $P,Q,R$   and $S$.
Which of the following statements are correct?
(i) $P$ is the luminous zone and is the hottest part of candle flame.
(ii) In zone $Q$, there is inadequate supply of oxygen.
(iii) Zone $R$ contains unburnt wax vapours produced by melting of wax.
(iv) In $S$ zone, carbon monoxide burns with a blue flame.

Mark the correct statement(s) among the following.
I. Water is a very good fire extinguisher as it cools down the fuels such as wood below its ignition temperature.
II. Water is a very good fire extinguisher for burning oils and electrical equipments.
III. Sand and soil may act as good fire extinguishers for burning oils.

Different methods of extinguishing a fire involve the following:
I. Removing the combustible substance.
II. Cooling the substance to a temperature below its ignition temperature.
III. Cutting off the supply of air.
Which of the following statement(s) is/are correct?

Neha took a burning candle and covered it with an empty glass by putting it upside down. She observed that the candle burns for some time before it finally goes off. What is the reason for this?

Natural resources are classified as:
P. Exhaustible
Q. Inexhaustible
Some natural resources are
(i) Petrol, diesel
(ii) Coal, petroleum
(iii) Air, water
(iv) Cow dung cakes, sunlight
(v) Forests, minerals
Which of the following represents the correct match?