Question

What Colour is monochrome?

Answer 1

Of an image, the term monochrome is usually taken to mean the same as black and white or, more likely, grayscale, but may also be used to refer to other combinations containing only tones of a single color, such as green-and-white or green-and-red.

Answer 2

How to Paint with One Color! / (Monochromatic Studies w/ Watercolors!)