If orange juice has a ph of 4, then it can be described as

Acid.

Explanation:

Acids may be defined as the substance that has the ability to release hydrogen ions in the solution. Acids has pH less than seven on the pH scale.

The orange juice has pH of 4. The pH of orange juice is less than seven. Hence, the orange juice is acidic in nature. Acids has the ability to convert the solution into the red color by the use of pH solution.

Thus, the correct answer is acid.