$61.\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_,\_\_\_\_\_\_\_\_\_\_\_\_\_,$ and $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ are common impurities found in refinery feedstock, which can adversely affect the efficiency and lifespan of refining equipment. $($a$)$ Sulfur, nitrogen, oxygen $($b$)$ Carbon, hydrogen, methane $($c$)$ Mercury, arsenic, lead $($d$)$ Butane, propane, ethylene

$62.$ The production of $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_,\_\_\_\_\_\_\_\_\_\_\_\_\_\_,$ and $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ involves the thermal or catalytic cracking of hydrocarbons to yield smaller, more valuable molecules. $($a$)$ Ethylene, propylene, butylene $($b$)$ Acetylene, synthesis gas, hydrogen $($c$)$ Naphthenes, aromatics, alkanes $($d$)$ Methanol, ethanol, propanol

$63.\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_,\_\_\_\_\_\_\_\_\_\_\_\_\_,$ and $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ are primary petrochemical precursors used in the production of a wide range of synthetic materials, including plastics, fibers, and rubbers. $($a$)$ Ethylene, propylene, butylene $($b$)$ Hydrogen, synthesis gas, acetylene $($c$)$ Methane, propane, butane $($d$)$ Polyethylene, polypropylene, polyvinyl chloride

$64.$ The main functions of $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_,\_\_\_\_\_\_\_\_\_\_\_\_\_,$ and $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ in petrochemical processes include serving as intermediates for various chemical reactions, as well as providing feedstock for the production of fuels and lubricants. $($a$)$ Ethylene, propylene, butylene $($b$)$ Synthesis gas, hydrogen, acetylene $($c$)$ Methanol, ethanol, propanol $($d$)$ Butadiene, styrene, vinyl chloride