1.
Arrange the given phenol and its derivatives in decreasing order of acidity:

(I) C6H5–OHC_6H_5\text{–OH}
(II) F–C6H4–OH\text{F–}C_6H_4\text{–OH}
(III) Cl–C6H4–OH\text{Cl–}C_6H_4\text{–OH}
(IV) O2N–C6H4–OH\text{O}_2\text{N–}C_6H_4\text{–OH}