$55.$ The process of $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ and $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ involves the conversion of hydrocarbons into smaller molecules through the application of heat and$/$or catalysts. $($a$)$ Steam cracking, catalytic reforming $($b$)$ Steam reforming, hydrocracking $($c$)$ Desalting, distillation $($d$)$ Polymerization, hydrogenation

$56.\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ and $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ are common methods used in the refining process to remove impurities and improve the quality of petroleum products. $($a$)$ Hydrotreating, catalytic cracking $($b$)$ Desulfurization, denitrification $($c$)$ Absorption, adsorption $($d$)$ Fractionation, distillation

$57.$ The primary application of $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ and $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ in the petrochemical industry is the production of various polymers and resins used in construction, automotive, and packaging industries. $($a$)$ Polyethylene, polypropylene $($b$)$ Methanol, ethanol $($c$)$ Ethylene, propylene $($d$)$ Butylene, acetylene

$58.\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ and $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ are common feedstocks used in the production of synthesis gas, which is a precursor for methanol, ammonia, and hydrogen. $($a$)$ Natural gas, coal $($b$)$ Crude oil, biomass $($c$)$ Methane, propane $($d$)$ Ethylene, propylene