Final answer:
The answer is true; atoms in the gas phase emit line spectra, which consist of light at specific, discrete wavelengths unique to each element, forming their distinct spectral signatures.
Step-by-step explanation:
True or false: line spectra are characteristic of atoms in the gas phase. The answer to this question is true. When a gas at low pressure is excited by an electrical current or is heated, it emits line spectra. This is due to atoms of each element emitting light at specific wavelengths unique to that element, leading to a spectrum featuring a series of discrete lines. Unlike a continuous spectrum that displays all wavelengths, a line spectrum contains only particular wavelengths of light, distinctive to each type of atom or molecule. This becomes the spectral signature of the gas. For example, when hydrogen gas is excited in such a way, it emits light that, after being passed through a prism, shows a line spectrum of four visible wavelengths. Neon lights and fluorescent bulbs are everyday examples of this phenomenon.