Red, due to the citric acid.
Apple juice is slightly acidic and therefore red litmus will not change color.
Litmus paper would turn red if apricot juice, which is acidic, was dropped on it. This is because litmus paper turns red in the presence of an acid.
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Blue litmus paper would turn red in orange juice.
Blue litmus paper turns red when grape juice is added, indicating that the solution is acidic.
Apple juice is a type of citric acid so it would turn blue litmus paper redish.
Potato juice is typically neutral or slightly acidic, so if you test it with litmus paper, blue litmus paper will remain blue, and red litmus paper will remain red. This indicates that potato juice does not change the color of either type of litmus paper, reflecting its neutral pH.
As orange juice being an acidic solution, it turns blue litmus into red.
blue
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Litmus paper will turn red in acidic solutions, such as orange juice, indicating its acidity.
When red litmus paper is dipped in grapefruit juice, it typically remains red. This is because grapefruit juice is slightly acidic, and red litmus paper does not change color in acidic conditions. If the juice were alkaline, the paper would turn blue, but grapefruit juice does not have that property.