Which statement about cracking is true?

Which statement about cracking is true?

• A. It converts long-chain alkanes into shorter-chain alkanes and alkenes.
• B. It increases the number of long-chain alkanes.
• C. It uses no catalyst and occurs at room temperature.
• D. It removes sulfur from hydrocarbons.

Answer: (A)

Cracking breaks apart large hydrocarbon molecules into smaller ones to increase the amount of more useful fuels. This process happens at high temperatures and often with the help of a catalyst, which speeds up the breaking of C–C bonds. When the long-chain alkanes crack, they produce shorter-chain alkanes and alkenes, because the breaking of the chain can leave saturated pieces (alkanes) and pieces with a double bond (alkenes) as products. For example, a long alkane such as a C12 molecule can crack into a C8 alkane and a C4 alkene, or into other combinations of shorter molecules. This explains why the statement about cracking being the conversion of long-chain alkanes into shorter-chain alkanes and alkenes is true. Cracking does not build more long-chain alkanes; it reduces them. It also does not occur at room temperature without a catalyst, since it requires high temperatures (and often a catalyst). And sulfur removal is a desulfurization step, not cracking.

Cracking breaks apart large hydrocarbon molecules into smaller ones to increase the amount of more useful fuels. This process happens at high temperatures and often with the help of a catalyst, which speeds up the breaking of C–C bonds. When the long-chain alkanes crack, they produce shorter-chain alkanes and alkenes, because the breaking of the chain can leave saturated pieces (alkanes) and pieces with a double bond (alkenes) as products. For example, a long alkane such as a C12 molecule can crack into a C8 alkane and a C4 alkene, or into other combinations of shorter molecules. This explains why the statement about cracking being the conversion of long-chain alkanes into shorter-chain alkanes and alkenes is true.

Cracking does not build more long-chain alkanes; it reduces them. It also does not occur at room temperature without a catalyst, since it requires high temperatures (and often a catalyst). And sulfur removal is a desulfurization step, not cracking.