Chemistry - GOC Question with Solution | TestHub

Squaric acid is cyclobutane-1,2,3,4-tetraone hydrate : it is strong because releasing the four-membered ring from angle strain drives deprotonation

Squaric acid is 3,4-dihydroxycyclobut-3-ene-1,2-dione : it is strong only because the two carbonyls withdraw inductively from the O-H bonds

Squaric acid is 3,4-dihydroxycyclobut-3-ene-1,2-dione : its monoanion is stabilised by resonance and intramolecular hydrogen bonding, and its dianion has four equivalent resonance structures that spread the charge over all four oxygens (quasi-aromatic stabilisation), so both protons are lost easily (pKa₁ ≈ 1.5, pKa₂ ≈ 3.4)

Squaric acid is a six-membered aromatic dioxo acid : it is strong because the ring is already aromatic before deprotonation