$51.\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ and $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ are common impurities found in refinery feedstock, which can lead to corrosion in equipment. $($a$)$ Sulfur, oxygen $($b$)$ Nitrogen, mercury $($c$)$ Carbon, hydrogen $($d$)$ Chlorine, arsenic

$52.$ The primary function of $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ and $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ in petrochemical processes is to provide heat for various reactions. $($a$)$ Synthesis gas, butylene $($b$)$ Hydrogen, acetylene $($c$)$ Steam, methane $($d$)$ Oxygen, propane

$53.$ The production of $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ involves the pyrolysis of hydrocarbons, resulting in the formation of carbon black, hydrogen, and other byproducts. $($a$)$ Ethylene $($b$)$ Propylene $($c$)$ Acetylene $($d$)$ Butylene

$54.\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ and $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ are common derivatives of ethylene, used in the manufacturing of various plastics. $($a$)$ Ethanol, butadiene $($b$)$ Polyethylene, polypropylene $($c$)$ Butylene, acetylene $($d$)$ Methane, propane