Question

Excited mercury atoms emit light strongly at a wavelength of 454 nm. This emission predominates when mercury atoms are excited in a flame. Predict the color of the flame.

Short answer

The color of the flame is blue.

Step-by-step solution

Theories behind colors

When light interacts with our eyes, we see different colors. When the electrons of an object absorb energy and get excited, we can see different colors. This excitation absorbs wavelength and we see their complementary colors.

Step 2: Prediction of the color of flame

Different colors have different wavelength ranges. For example, violet has a wavelength range of $380-450\text{\hspace{0.17em}nm}$, blue color has a wavelength range of $450-495\text{\hspace{0.17em}nm}$, green color has a wavelength range of $495-570\text{\hspace{0.17em}nm}$ etc.

The given wavelength is 454 nm. So it lies in the range of blue in the spectrum.