Explanation

(d) A series of notes arranged, such that their fundamental frequencies have definite ratios is called a musical scale. In 1588, Zarlino constructed a musical scale by introducing sis notes between an Octave. These eight notes constitute major diatonic scale. The first one note or the note of the lowest frequencies is called keynote and ratio of the frequencies of the two notes is called interval between them. It means two octaves higher means four times the given frequency.
∴ Required frequency=4×128=512 Hz