the top
The external part of the flame is the coolest.
The blue part of the flame, the cone in the middle is the hottest, the flame cools as it gets further away from the burning centre, this is similar to the sun where the outer surface of the sun is significantly cooler compared to the inside.
To change the flame of a Bunsen burner you must open or close the air valve, usually this is done by rotating the barrel.
It's the part of the Bunsen burner which lets in air, adjusting the strength of the flame. basically the hole at the bottom with the twisty bit.
outer oxidising zone is the second most hottest part of burner flame....
The coldest part of the Bunsen Burner would be the gas inlet nozzle. Since expanding gasses absorb quite a bit of heat, the coldest portion would be where the gas first enters the burner. Now "whats the coldest part of a Buseb burners flame?", a completely different question. It' s the part closest to the ignition point.
the tip
The tip of the blue cone is the hottest part of the Bunsen burner flame.
Fire
In the fire
The external part of the flame is the coolest.
hottest part of flame
The moving part of the bunsen burner adjusts the amount of air intake. This changes the appearance and heat of the flame.
Near the tip of a blue flame is the hottest.
For a Bunsen burner the lowest temperature is in the extreme lower part of the flame.
in bunsen burner complete combustion takes place,it produces blue flame and blue region is the hottest part of a flame.so the whole flame is very hot,either the outermost part of flame.
A properly adjusted flame on a bunsen burner would have a flame that is blue. It would also appear that there is a lighter blue flame in the center, usually referred to as an inner blue cone, the hottest part of the flame.