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Which gas is commonly used in electric bulbs to prevent the oxidation of the tungsten filament?
Hydrogen
Nitrogen
Oxygen
Carbon Dioxide
Nitrogen
Electric bulbs are filled with inert or inactive gases like nitrogen or argon to prevent the tungsten filament from burning away. At high temperatures, tungsten reacts readily with oxygen to form tungsten oxides, which would cause the filament to become brittle and eventually break.
Electric bulbs are filled with inert or inactive gases like nitrogen or argon to prevent the tungsten filament from burning away. At high temperatures, tungsten reacts readily with oxygen to form tungsten oxides, which would cause the filament to become brittle and eventually break.
Think of it like a vacuum-sealed food bag; removing or replacing the air with a non-reactive gas stops the food from spoiling, just as replacing the air in a bulb stops the filament from 'spoiling' by burning out.
N-A-I: Nitrogen, Argon, Inert (Gas).
2W+3O2тАЛтЖТ2WO3тАЛ тАФ Represents the oxidation process of tungsten (W) that leads to filament failure.
The filament reaches temperatures exceeding 2000┬░C during operation. In the presence of oxygen (O2тАЛ), oxidation occurs: 2W+3O2тАЛтЖТ2WO3тАЛ. By filling the bulb with an inert gas like Nitrogen (N2тАЛ) or Argon (Ar), the concentration of reactive oxygen is minimized, effectively preventing the combustion and sublimation of the tungsten metal.
Tungsten is used for filaments due to its extremely high melting point of approximately 3422┬░C.
Nitrogen and Argon are chemically inactive (inert) under bulb operating conditions.
The pressure inside a filament bulb is often kept slightly lower or equal to atmospheric pressure using inert gases to balance structural stress.
Significantly increases the lifespan of the tungsten filament.
Prevents rapid evaporation/sublimation of the filament metal.
Inert gas filling causes heat loss via convection, which slightly reduces the luminous efficiency compared to a perfect vacuum.
Incandescent light bulbs
Halogen lamp technology
Argon is often preferred over Nitrogen for higher-wattage bulbs as it has lower thermal conductivity, further reducing heat loss.
Oxygen (Option C) would cause the filament to oxidize and burn instantly. Hydrogen (Option A) is highly flammable and reactive at high temperatures. Carbon Dioxide (Option D) would react with hot tungsten to form tungsten carbides.
B is correct тАФ Nitrogen is an inert gas that creates a protective, non-reactive environment for the hot tungsten filament.
In competitive exams, remember that Noble gases (Group 18) are the most inert, but Nitrogen (N2тАЛ) is also widely used in industries due to its strong triple bond (NтЙбN), which makes it relatively unreactive at standard conditions.