Answer:
pH = 1.1
Explanation:
number of moles of KHP = 0.4/204.2 = 0.002
KHP ⇒ k⁺ + HP⁻
HP⁻ + H₂O ⇒ P⁻ + H₃O⁺
1 mole of KHP disolves in water and produces 1 mole of H₃o⁺
so 0.002 of KHP produce 0.002 mole of H₃O⁺
the concentration of H₃O⁺ = 0.002/(25/1000) = 0.08
pH = -log(0.08) = 1.1