two divers are swimming in clear ocean water at a depth of 150 m. The first diver is wearing a white wet suit. When the second diver sees the first diver at that depth, which of the following colors would he see?

The second divers is going to see COLOR BLUE.
Water has the ability to transform light, thus colors appear differently in water. Generally, water absorbs warm colors and scatter the cooler colors. In clear ocean water, visible light decreases approximately 10 folds for every 75 meters that one descend. Thus, at the depth of 150 M, the white suit will appear to be blue in colour.

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MrBrainalot MrBrainalot · Answer 2 · 2017-11-24T05:00:15+01:00

Note the question is missing the multiple choice answers to choose from, however, we can still provide a meaningful answer.

Light from the sun is a composite of a full spectrum of light, ranging from very long wavelengths (such as radio waves) all the way to very short wavelengths (such as xrays and gamma rays). Visible light - the light we can see - occupies a tiny slither of the electromagnetic (light) spectrum and ranges from blue/violet (around 400nm wavelength) up to red (around 700nm wavelength).

Now back to the question. Water is much more dense than space or air, and as a result, water causes light to attenuate when it passes through it. This means parts of the light are absorbed as they travel through the water medium. Generally, higher energy light has more penetrative power and the energy contained in light is proportional to it's wavelength; the shorter the wavelength the higher the energy. This means blue light (400nm) is higher in energy than red light (700nm). So, as light passes though water, the lower energy wavelengths are attenuated (absorbed) first. This means red disappears first, then followed by orange, yellow, green, and finally blue and ultraviolet. At 150m depth, depending on how clear the water is, only blue light would remain and it would be quite dark.