Final answer:
The emission spectrum of an isolated gas is composed of discrete frequencies corresponding to the quantized energy levels of the gas, unlike white light which is a continuous distribution of frequencies.
Step-by-step explanation:
The emission spectrum of an isolated gas differs from the emission spectrum created by white light because they are fundamentally different in their composition.
White light is a continuous distribution of frequencies, meaning it contains a full rainbow of colors, which are observable when the light is passed through a prism.
Conversely, an isolated gas has quantized energy levels, and when electricity is passed through such a gas, only certain colors are emitted, corresponding to these energy levels.
This results in an emission spectrum that is a series of discrete frequencies, or a line spectrum, unique to each type of gas.
A classic example of this is the emission spectrum of hydrogen, where an electrical discharge through the gas at low pressure produces a line spectrum visible as four distinct colored lines when viewed through a prism.