Four conditions which cause a metathesis reaction to occur?

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.

0.2348 grams of pbcl2 used to form 44.0 ml of solution.

Connect the whole numbers on the periodic table to indicate what they represent?