Is anyone here good at chem and would be able to help me with a lab :3

Which is the layer underground where all empty spaces are filled with a combination of air and water ?

The covalent compound acetylene, which is the fuel of the oxyacetylene torch used by welders, has the molecular formula c2h2. the covalent compound benzene, a commercial solvent, has the molecular formula c6h6 each of these covalent compounds contains carbon and hydrogen atoms in a one-to-one ratio. would it be correct to write the chemical formulas of each as ch? explain.

An experimental procedure requires a 10 ml of acid to be dissolved