The rate of conversion (R) of ferrous ions to ferric ions by dissolved oxygen in the presence of bacteria is a first order reaction with respect to ferrous ions in the concentration (C) range of 0.1 0.6 mol L-1. The rate of oxidation of 0.6 mol L-1 ferrous ions is 0.25 mol L-1 min-1. Select the correct statement: (1) First order rate constant (k) for the oxidation reaction can be calculated using R = kC. (2) Time taken for 70% conversion of ferrous ions at an initial concentration of 0.6 mol L-1 in a plug flow (tubular) reactor can be calculated using Ct = Co exp(-kt) (3) Residence time of a mixed flow reactor (CSTR) that would be required for 70% conversion of 0.6 mol L-1 ferrous ion feed can be calculated using Ct = Co (1+k)-1 (4) All statements are correct (5) Only (1) and (3) are correct