Question

why an electric bulb is filled with nitrogen on algal going instead of

Answer 1

It depends on the type of the bulb:
 
1) Incandescent bulbs:
   low wattage types are vacuum or argon/nitrogen mix
   medium wattage types are ~90% argon with ~10% nitrogen added to prevent arcing
   there was a subset of 'high efficiency" bulbs that were filled with krypton - popular in the 1930-1950 timeframe and 10% nitrogen
 
2)  Halogen bulbs are filled with argon and small amount of halogen containing gas such as methyl bromine or methylene bromine
 
3) low pressure discharge lamps ( fluorescent lamps)  are filled with argon or some special types such as signage are filled with neon
 
4) high pressure discharge lamps are filled with argon
 
5) high intensity arc lamps ( e.g a movie projector lamp and some car headlight lamps)  are filled with xenon

Answer 2

You Cannot fill the bulb with air or hot tungsten wire because it will com bust in presence of oxygen. You can,t maintain vaccuum either or external atmosphere will break thee glass. So that is why we have to fill the bulb with Nitrogen(N) because it is non-reactive gas. Nitrogen does not react with hydrogen to form ammonia, It needs a very large amount of heat and catalyst (usually nickel) and yet, the yield is only 50%. We can also use some inert gases like Helium or argon instead of nitrogen but they are more expensive and rarer than nitrogen.
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