Electron withdrawing substituent increases the acidity by increasing the ionic character of −OH by inductive effect. Electronegativity decreases in the order. F>Cl>Br -I effect also decreases in the same order. Thus, the correct sequence is FCH2COOH>ClCH2COOH>BrCH2COOH>CH3COOH Related Theory I effect is a permanent effect & generally represented by an arrow on the bond.