What might happen if the ozone layer did not block the Sun's ultraviolet Rays? The surface of the Earth would be much hotter. Devices that use electromagnetic radiation would no longer work. Humans would be able to see in the ultraviolet range of the EM spectrum.

The surface of the Earth will become hotter.

Explanation:

The surface of the Earth will become hotter if the ozone layer does not block the sun because ozone layer is a layer of the Earth's stratosphere that act to block or absorb the dangerous ultraviolet radiations or Ray's produced by the sun. When it absorb it, the dangerous radiations will not get to the Earth and the Ray's produced by sun coming to the Earth is minimal and it is in quantity that it is favourable for humans,plants and animals. Without ozone layer blocking the sun, the Earth surface will be hotter and Inconducive for survival of living organisms.