$9.$ True or False: Hydrogenation is a refining process used to remove sulfur from petroleum products.

$10.$ True or False: Isomerization is a process used in refining to convert straight$-$chain hydrocarbons into branched$-$chain hydrocarbons.

$11.$ True or False: A fluid catalytic cracking unit in a refinery produces lighter hydrocarbons from heavier ones.

$12.$ True or False: Synthesis gas can be used to produce a variety of chemicals, including methanol and ammonia.