TURTLE ROCK SCIENTIFIC / SCIENCE PHOTO LIBRARY TURTLE ROCK SCIENTIFIC / SCIENCE PHOTO LIBRARY
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Testing toothpaste for alkalinity. Universal indicator changes its colour depending on the pH. Here a universal indicator paper strip has changed colour from yellow to blue-green after coming in contact with toothpaste that contains sodium bicarbonate (NaHCO3). The test shows that the toothpaste is slightly alkaline.
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