Does baking soda and citric acid form a precipitate?

No, baking soda (sodium bicarbonate) and citric acid do not form a precipitate when combined. Instead, they react to produce carbon dioxide gas, water, and sodium citrate. The chemical reaction between baking soda and citric acid can be represented as follows:

NaHCO3 (baking soda) + H3C6H5O7 (citric acid) → CO2 (carbon dioxide) + H2O (water) + Na3C6H5O7 (sodium citrate)

The sodium citrate produced in the reaction is soluble in water, so it does not form a precipitate. The carbon dioxide gas produced causes bubbles to form, which is why baking soda and citric acid are often used as leavening agents in baking.