Final answer:
Citric acid does release hydrogen gas when mixed with baking soda.
Step-by-step explanation:
When citric acid is mixed with baking soda, it does release hydrogen gas. Citric acid is an acid and baking soda is a base, so when they react, they undergo an acid-base reaction called neutralization. In this reaction, citric acid donates a hydrogen ion (H+) to the baking soda, which causes the release of hydrogen gas (H2).