$5.$ Which of the following is a primary component of natural gas?

A$)$ Methane

B$)$ Ethanol

C$)$ Butane

D$)$ Diesel

$6.$ Which of the following is a petrochemical precursor used in the production of plastics?

A$)$ Synthesis gas

B$)$ Acetylene

C$)$ Hydrogen

D$)$ Ethanol