$7.$ Hydrocracking is distinguished by its use of $\_\_\_\_\_\_\_\_$ under high $\_\_\_\_\_\_$ and $\_\_\_\_\_\_\_\_,$ with the aid of a catalyst, to produce cleaner fuels and other petroleum products.

$8.\_\_\_\_\_\_\_\_$ reforming, a type of petroleum refining process, employs high temperatures and $\_\_\_\_\_\_$ pressures to rearrange or $\_\_\_\_\_\_\_\_$ the molecular structure of hydrocarbon fractions to enhance fuel quality.

$9.$ During catalytic reforming, a $\_\_\_\_\_\_\_\_$ is used to convert naphthenes into aromatics, thus improving the $\_\_\_\_\_\_$ and $\_\_\_\_\_\_\_\_$ of gasoline, which are crucial for modern engines.

$10.$ The alkylation process in refining involves combining $\_\_\_\_\_\_\_\_$ and $\_\_\_\_\_\_$ in the presence of an acidic $\_\_\_\_\_\_\_\_$ to produce high$-$octane number components for gasoline.