Sodium (Na)
Oxygen (O2)
Strontium is the element that turns a flame carmine red when it is burned. When strontium is present in a flame, it imparts its characteristic red color due to the emission of specific wavelengths of light.
The hottest part is where the flame is light blue or blue; which gradually turns to yellow as the flame is cooled by the colder outer air. When the safety flame (yellow) is on, the hottest point is the tip of this flame.
Potassium although sometimes it can look purple
Lithium turns red in flame tests.
the color of mercury is gray it has no color
Different elements added to a fire can change its color. For example, copper can produce a blue flame, while potassium can create a purple flame. The temperature required to produce these colors can vary depending on the specific element being used.
The salt in the air from the sea, turns a camp fire flame blue as it is lit, it then retearns to normal.
Sulfur turns yellow when heated.
To get a blue flame with a Bunsen burner, ensure the air intake is fully open by turning the collar at the base of the burner counterclockwise to allow more oxygen into the mixture. Adjust the gas flow to achieve a blue, well-defined flame with minimal yellow tip. If the flame is too yellow, increase the air intake until it turns blue.
At least in the USA, a red light does not turn yellow. It turns green. A green light turns yellow, and then the yellow light turns red. IN THAT ORDER.
When you close the air valve of a Bunsen burner the flame turns yellow due to incomplete combustion and the ignition of carbon particles (soot).