Which food contains more acid out of frozen peas rice pudding pickled onions and chips?

Here's why:

* Pickled onions are preserved in vinegar, which is a highly acidic solution.

* Rice pudding is typically made with milk and sugar, which are less acidic.

* Frozen peas have a neutral pH.

* Chips (potato chips) are generally salty, with little acidity.

While the other foods may contain some level of acidity, the high vinegar content in pickled onions makes them significantly more acidic than the other options.