$45.\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ is a petrochemical precursor primarily used in the production of synthetic rubber. $($a$)$ Ethylene $($b$)$ Butylene $($c$)$ Propylene $($d$)$ Acetylene

$46.$ The primary purpose of $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ in the petrochemical industry is to serve as a precursor for various chemicals such as methanol and ammonia. $($a$)$ Synthesis gas $($b$)$ Hydrogen $($c$)$ Ethylene $($d$)$ Butylene

$47.$ The process of $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ involves the conversion of methane and steam into synthesis gas. $($a$)$ Steam cracking $($b$)$ Steam reforming $($c$)$ Catalytic reforming $($d$)$ Hydrocracking

$48.\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ is a common petrochemical product derived from naphthenes, commonly used as a fuel for automobiles. $($a$)$ Diesel $($b$)$ Gasoline $($c$)$ Jet fuel $($d$)$ Propane