Answer:
H₂O
Explanation:
According to Arrhenius Concept of Acid and Base, "Acid is any specie which when dissolved in water ionizes to produce H⁺ ions".
Examples:
HCl → H⁺ + Cl⁻
H₂SO₄ → 2 H⁺ + SO₄²⁻
While, "Bases are those species which when dissolved in water produces Hydroxyl Ions (OH⁻)".
Examples:
NaOH → Na⁺ + OH⁻
Mg(OH)₂ → Mg²⁺ + 2 OH⁻
Given Options:
CH₃OH:
Methanol when dissolved in water does not dissociate as follow,
CH₃OH → H₃C⁺ + OH⁻
Hence, it does not behave as Arrhenius Base.
CH₃COOH:
Acetic acid when dissolved in water produces H⁺ ions and Acetate ions i.e.
CH₃COOH → CH₃COO⁻ + H⁺
Therefore, it can act as Arrhenius Acid instead of Arrhenius Base.
H₂O:
Water when dissolved in water dissociates as,
H₂O → H⁺ + OH⁻
As it is producing both H⁺ and OH⁻ ions therefore, it can act as both Arrhenius Base and Arrhenius Acid.
H₂NNH₂:
Hydrazine when dissolved in water can neither produce OH⁻ ions nor H⁺ ions hence, it is neither Arrhenius Base nor Arrhenius Acid,
