1) Acidic - gastric juices pH 1, lemon juice pH 2.2, tomato juice pH 4.
2) Neutral - salt solution pH 7.
3) Alkaline - baking soda pH 9, bleach pH 13.
pH is a numeric scale used to specify the acidity or basicity of an aqueous solution.
When pH is less than seven (pH<7), solution is acidic.
When is equal seven (pH = 7), solution is neutral.
When pH is greater than seven (pH > 7), solution is basic.
The melting of the ice cube indicates physical change has taken place
It became thicker and its viscosity decreased and cannot flow as easily as before.
You ignite a chemical reaction by adding the borax solution to the glue mixture.
In a chemical reaction, the molecules of glue and borax combine to form a flexible, springy new substance. With rubber's vulcanization serving as a model, chemical cross-linking has been extensively employed to change the physical properties of polymeric materials.
Chemical links between polymer chains provide a substance with a more solid structure and perhaps a better-defined shape. It thickened and lost viscosity, making it more difficult to flow than it once could.
Learn more about the chemical reaction here brainly.com/question/16714866
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