In a harmonium the intermediate notes between a note and its octave form is:
(A) An arithmetic progression
(B) A geometric progression
(C) A harmonic progression
(D) An exponential progression

Hint:In a harmonium an octave is defined as the interval between one musical pitch and another. So, the question basically implies what type of equation should be between an intermediate note and a note and its octave form. This can be easily remembered by using the expression.

Step by step Solution:
The intermediate notes between a note and its octave form will always be in a geometric progression as each note after the first can be found out by multiplying the previous note by a fixed intermediate note. Thus, the progression formed in the end resembles that of a geometric progression and not a harmonic progression as many students wrongly perceive.

Additional Information:A harmonic progression is only formed when any note in the harmonium or any other musical instrument is the harmonic mean of its two neighbour notes. In a harmonic progression the overall progression is ultimately simple harmonic. A harmonium or harmonica works on geometric progression and not simple harmonic progression as the name wrongly suggests.

Note:It is important to remember the difference between a harmonic progression and an arithmetic, geometric or exponential progression. Most students usually confuse the intermediate notes between a note and its octave form and write the answer as harmonic simply because the name harmonium or harmonica suggests so. This is however not the case and the student should firmly believe in the mathematical part and not go in the wrong direction with any question. Mathematically the progression is geometrical and not harmonic.