RRB RPF RPSF SI and CONS Model Papers 5 with solutions

(2) Oxalic acid $\left({\mathit{C}}_2{\mathit{H}}_2{\mathit{O}}_4\right)$ solution is used to remove rust stains on cloth. Rust reacts with oxalic acid to produce a colorless, water-soluble complex ion (i.e., ${\left[\mathit{F}\mathit{e}{\left({\mathit{C}}_2{\mathit{O}}_4\right)}^3\right]}^{3-}$ ) which contains the bidentate ligand, oxalate ion. Because the complex ion is water-soluble it can be washed away.