Q: Which of the following statements are true?
I. Yellow Flames are ideal for heating.
II. The substances whichvaporiseduring burning, gives flames.
III. Luminous Zone contains unburnt carbon particles.
IV. The non-Luminous Zone has highest temperature.
OPTIONS ARE: - I, II and IV
- I, II and III
- I, III and IV
- II. III and IV
The correct option is II only.
The blue flame is ideal for heating
Non-luminous zone contains unburnt particles.
Luminous zone has highest temperature.
Read the following text for same.
Flame is defined as a glow that is produced when a substance undergoes combustion. Flame is produced only by that substances which vapourise during burning. For example, kerosene oil and molten wax rise through the wick and are vapourised during burning and form flames. Charcoal, on the other hand, does not vapourise and so does not produce a flame.
There are basically two types of flame - luminous flame and non-luminous flame. Luminous flame (also known as blue flame) is observed when a fuel is burnt in sufficient supply of oxygen, leading to complete combustion of the fuel. This type of flame is observed in a gas stove, where LPG is the fuel. The flame appears blue in colour.
Non-luminous flame, on the other hand is the flame which results from the incomplete combustion of fuel, when a fuel is burnt in limited supply of oxygen. This flame appears yellow in colour due to deposition of unburnt carbon particles. This is observed in the flame of a kerosene lamp, where kerosene is the fuel.