A long-chain alkane, octadecane (C18H38\text{C}_{18}\text{H}_{38}C18H38), is catalytically cracked to produce one molecule of heptane (C7H16\text{C}_7\text{H}_{16}C7H16), two molecules of a compound Y, and one molecule of compound Z. Compound Y is an alkene containing three carbon atoms.
State the molecular formula of compound Y.
Deduce the molecular formula of compound Z.
State two conditions required for industrial catalytic cracking.