How does the frequency of a beam of ultraviolt light change when it goes from air to glass?

How does the self inductance of an air coil change, when the number of turns in the coil is decreased?

How does the self inductance of an air coil change, when an iron rod is introduced in the coil?

What happens to the wavelength of light when it goes from rarer to denser medium?

How does the pH of an acid solutoin change when it is diluted?

What fraction of revolution clockwise does the hour hand of a clock turn through when it goes from: 9 to 3.

What fraction of revolution clockwise does the hour hand of a clock turn through when it goes from: 12 to 3