how come you can't see pink in the rainbow but you can see it in a soap bubble?

There are two different kinds of colors. Those that are in the rainbow or spectrum are the primary colors and can be reproduced by light with a single wavelength. they are red orange yellow green blue indigo violet. And the graduations between them.

But those are not the only colors possible. Mixtures of light from various parts of the spectrum are examples, such as the achromatic colors (black, gray and white) and colors such as pink, tan, and magenta. You won't find any of these in the rainbow, yet they are very common colors.

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It's to do with the wavelength of light that's refracted through a soap bubble compared to a water droplet.