Final answer:
The statement is false; the fifth tone or harmonic does not determine the identity or 'mark' of a sound. Timbre is influenced by the frequencies of all the harmonics present, not solely by the position of a tone within the harmonic series.
Step-by-step explanation:
The statement that if you hear the same sound twice, the second sound will have a mark because it is the fifth tone is False. In acoustics and music, a sound's identity or mark, often referred to as its tone quality or timbre, isn't solely determined by it being a fifth tone.
A sound is characterized by its frequency, and the 'fifth tone' typically refers to its harmonic relationship to a fundamental frequency, not a repetition of the sound. The fifth harmonic, or fifth tone, is actually three times the frequency of the fundamental tone if you are referring to the series of overtones in a harmonic series. For example, if the fundamental frequency is 100 Hz, the fifth harmonic would be at 500 Hz. However, the idea of a 'mark' seems to be based on a misinterpretation of musical or acoustic principles.