Rank the types of visible light in order from longest to shortest wavelength?

Red
Orange
Yellow
Green
Blue
Indigo
Violet

Red being the longest
Violet the shortest

11.07 g/cm³

Explanation:

Using the first difference in mass we can calculate the volume it takes to fill up the pycnometer:

35.55 - 25.60 = 9.95 g of water

9.95 g / 0.9982g/mL = 9.9679 mL

In order to calculate the volume occupied by lead, we calculate the volume of water, using again the difference in mass:

44.83 - 10.20 - 25.60 = 9.03 g water

9.03 g / 0.9982g/mL = 9.0463 mL water

The volume that is not occupied by water, is occupied by lead:

9.9679 - 9.0463 = 0.9216 mL

With the volume occupied by lead, and the mass, we can calculate the density of lead, keeping in mind that 1 mL = 1 cm³:

10.20 g / 0.9216 cm³ = 11.07 g/cm³.