Final answer:
The suggested chemical approach to dissolve seashells in underground pipes quickly is using high-strength acid drain cleaner containing concentrated sulfuric acid.
Step-by-step explanation:
In order to dissolve seashells in underground pipes quickly, high-strength acid drain cleaner containing concentrated sulfuric acid is suggested in the given context. Sulfuric acid is a strong acid that can react with calcium carbonate, the main component of seashells, to form a soluble salt and water:
H2SO4 + CaCO3 → CaSO4 + H2O + CO2
This chemical approach is effective in dissolving seashells and clearing clogs in pipes.