Find the resultant molarity obtained by mixing the following
(i) 2 litre, 0.5 M HCl `+ 3` litre, 0.2 M HCl
(ii) 500 ml, 1M NaCl `+ 200 ml, 2M NaCl`
(iii) 100 ml, 0.1 M NaOH + 400ml, 0.2 M NaOH
(iv) 2 litre, 0.2 M HCl `+ 500 ml, 0.4 m HCl`