Why does seltzer react with lemon juice?

Seltzer reacts with lemon juice due to the presence of carbon dioxide (CO2) in the seltzer, which creates carbonation. When lemon juice, which is acidic, is added to seltzer, it can cause the carbon dioxide to escape rapidly, producing bubbles and fizz. This reaction is a result of the acid in the lemon juice interacting with the carbonated water, leading to the release of gas. The visible fizzing is a fun demonstration of the interaction between an acid and a carbonated beverage.