101.000 convert the fowloing number in scientific notation

The answer for #3 is c but i don't know why

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.

Asolution contains 180 g of glucose (c6h12o6) and 162 g of water. what is the mole fraction of glucose?