How would a rainbow be created with Waves and Mediums?

Which of the following are guidelines to follow for obtaining accurate observations

Glass has a hardness that is in the middle of the hardness scale. what is the hardness of glass?

Avertical clean glass piezometer tube has an inside diameter of d = 1 mm and is used to measure pressure in a horizontal pipe carrying water as shown. due to pressure in the pipe, the water at 20c rises into the tube to a height h. if the water pressure in the pipe is p = 500 pa gauge, estimate the height h: (a) without considering surface tension (b) with surface tension (capillary) effects. the contact angle  can be assumed at 30 deg