$5.$ 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

$7.$ What is the main component of synthesis gas?

A$)$ Carbon dioxide

B$)$ Methane

C$)$ Carbon monoxide

D$)$ Ethylene

$8.$ Which of the following is NOT a petrochemical precursor?

A$)$ Butylene

B$)$ Acetic acid

C$)$ Ethylene

D$)$ Propylene