Question

Sand and chalk are in water

Answer 1

Answer:

will form a suspension

Answer 2

Chalk is usually close to pure calcium carbonate. “Sand” is normally assumed to be quartz sand so almost pure silicon dioxide. The sand will sink to the bottom pretty quickly. The chalk will also mostly settle out but the finer grains may stay in suspension - prevented from falling to the bottom by random collisions with the water molecules. A tiny proportion of the chalk will dissolve and another tiny proportion may react with dissolved carbon dioxide (in the form of carbonic acid).

At the bottom of your container will be a layer of mostly sand together with a proportion of chalk and above tgat a layer of chalk.