Which molecule is considered a base in the lewis model, but not in the brønsted-lowry or arrhenius model? po43− naoh nh3 na2s

Explanation: According to Arrhenius concept, a base is defined as a substance which donates hydroxide ions when dissolved in water and an acid is defined as a substance which donates hydronium ions in water.

According to the Bronsted Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and a base is defined as a substance which accepts protons.

According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.

Thus is a lewis base as it contains a lone pair of electrons and thus can donate it.

i'm pretty sure its b i might be wrong though!