What is always produced when an alkane undergoes cracking?

When an alkane undergoes cracking, it breaks down into smaller hydrocarbon molecules, which typically include smaller alkanes and alkenes. The cracking process involves the thermal decomposition of larger alkane molecules, which results in the production of these smaller hydrocarbons.

Alkenes are particularly significant because they are unsaturated hydrocarbons, meaning they have at least one double bond between carbon atoms, making them more reactive than alkanes. Smaller alkanes can be useful as fuels, while alkenes serve as important intermediates in the production of plastics and other chemicals.

The formation of smaller alkanes and alkenes is a key aspect of the cracking process, thereby affirming the correctness of the selected answer. The other options do not accurately represent the products of the cracking process; for example, hydrogen gas alone is not a consistent product, and neither are only larger hydrocarbons or carboxylic acids typically produced.