Answer:
On a 10-fold dilution of a strong acid, the pH will increase.
Proof:
Lets take initial concentration of Acid as 10 M, So, as
pH = - log [H⁺]
Putting value of [H⁺]
pH = - log (10)
pH = -1
After 10 fold Dilution, the concentration iwill be 1 M, So,
pH = - log [H⁺]
Putting value of [H⁺]
pH = - log (1)
pH = 0
So, with 10 fold dilution the pH increases.