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