Answer:
Art can't be defined because art is the work of creativity anything that has creativity or passion could be art.
Answer: The account of the travels of the Muslim legal scholar Ibn Battuta in the first half of the 14th century reveals the wide scope of the Muslim world at that time.
Explanation: https://www.khanacademy.org/humanities/big-history-project/expansion-interconnection/exploration-interconnection/a/ibn-battuta
Answer:
Middle C (the fourth C key from left on a standard 88-key piano keyboard) is designated C4 in scientific pitch notation, and c′ in Helmholtz pitch notation; it is note number 60 in MIDI notation.
B) herman von helmholtz
The trichromatic color theory<span> began in the 18th century, when </span>Thomas Young<span> proposed that color vision was a result of three different </span>photoreceptor cells<span>. </span>Hermann von Helmholtz<span> later expanded on Young's ideas using color-matching experiments which showed that people with normal vision needed three wavelengths to create the normal range of colors. Physiological evidence for trichromatic theory was later given by </span>Gunnar Svaetichin<span> (1956).</span>