Q. The substance used as a smoke screen in war fare is

 2777  185 AIPMTAIPMT 1989The p-Block Elements Report Error

Solution:

Actually, is formed there along with acetylene under the reaction of with where, the phosphene reacts with acetylene formed and catches fire to get smoke which forms the smoke screen. In Holme's signal, the calcium phosphide and calsium carbide is thrown in sea where the reaction produces phosphene gas and acetylene and the phosphene catches fire with acetylene and forms smoke which sends the signal.
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