Answer:
a. Na+ is pH neutral
b. Ni2+ = weak acid
c. NH4+ = Weak acid
Explanation:
To know the nature of the cation we need to find the nature of its conjugate base.
If the conjugate base of the ion is a strong base, the ion is neutral.
If the conjugate base is a weak base, the ion is a weak acid:
a. Conjugate base Na+ = NaOH
Sodium hydroxide is a strong base:
Na+ is pH neutral
b. Conjugate base Ni²⁺: Ni(OH)2 is a weak base because is not completely soluble in water. That means:
Ni2+ = weak acid
c. Conjugate base NH4+: NH4OH. Weak base:
NH4+ = Weak acid
