Question

Why do you have a sour taste in your mouth when you vomit?

Answer 1

Hint: The uncontrollable, forceful evacuation of one's stomach contents through the mouth and sometimes the nose is known as vomiting (also known as emesis and throwing up). Projectile vomiting is a severe form of vomiting that might include vomit coming out of the nose and is sometimes seen in neonates.

Complete answer:
Nausea can be caused by multiple factors. Pregnancy, drug use, food poisoning, and infection are examples of these. Nausea might range from mildly unpleasant to severe enough to interfere with your regular activities.
Vomitus (expelled stomach contents) contains not just the food we've eaten, but also mucus from our stomach lining, pepsinogen (a protein-breaking enzyme), and hydrochloric acid. The taste of something (edible) is one of the features we use to detect if it is acidic. Acids taste sour. Consider lemons, vinegar, apples, tomatoes, and raspberries; all of these are sour to us. The acid in our stomach, hydrochloric acid, is similar, but much stronger (pH of 0.5-1.0).
Bases, on the other hand, taste bitter because their pH is larger than 7.0. (You may get a fair notion of how "bitter" feels by putting a small amount of baking soda on your tongue.)

Note:
Though the terms are commonly used interchangeably, vomiting and regurgitation are not the same. Regurgitation is the return of undigested food to the mouth through the oesophagus without the force and discomfort of vomiting. Vomiting and regurgitation are caused by a variety of factors.