Question

if a handful of soil added to water in a glass stirred well and left undisturbed for some time four different layers are formed they are humus sand gravel and clay
arrange these layers in order from top to bottom

Answer 1

The bottom layer will be the sand part of the soil. If there are any pieces of stones this will also settle down at the bottom. Next up is the silt. Silt is lighter than sand and so will come above it. If you were able to separate out any clay particles they will be the smallest and will be at the top. But if your soil is really thick clay then you may just be left with clay lumps at the bottom. And next up is the water. This is likely to be discolored due the color of the soil.
AND THAT IS HOW SOIL IS SEPARATED.