Which of the following does not show any flame test?

Magnesium (Mg) and beryllium do not show characteristic flame colors because the energy gap between their ground and excited states is too large to be bridged by flame energy. Other alkaline earth metals (Ba, Ca, Sr) give distinctive flame colors - barium (green), calcium (brick red), and strontium (crimson red). This property is why Mg is used in flares and fireworks to produce bright white light without color.