The sodium salt shown is heated strongly with soda lime ($\mathrm{NaOH}$ and $\mathrm{CaO}$). Which hydrocarbon is formed?

The compound shown is sodium benzoate. Soda lime decarboxylation replaces the $\mathrm{COONa}$ group by H, giving benzene and sodium carbonate. Biphenyl would be a coupling (Kolbe-type) product, and toluene would need an extra carbon.