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2 answers:
The pH scale was given by Sorensen to quanitatively define strength of an acid and base
the pH scale extends from 0 to 14
For acids
The pH should be less than 7 [always]
For base
The pH should be more than 7 [always]
The pH seven is of neutral solution
pH = -log[H+]
Thus lower the pH higher the concentration of hydronium ion or protons produced by an acid
thus for the given pH scale interval [0-3] it represents strong acid [Which will give high concentration of protons on dissociation]
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