Free iodine is titrated against standard reducing agent usuallywith sodium thiosulphate , i.e. K_(2)Cr_(2)O_(7) + 6Kl + 7H_(2)SO_(4) to Cr_(2)(SO_(4))_(3) + 4K_(2) SO_(4) + 7H_(2)O+l_(2) 2CuSO_(4) + 4Kl to Cu_(2)l_(2) + 2K_(2)SO_(4) + l_(2) l_(2) + Na_(2)S_(2)O_(3) to 2Nal + Na_(2)S_(4)O_(6) In iodometric titration, starch solution is used as an indicator. Starch solution gives blue or violet colour with free iodine .At the end point , blue or violet colour disappears when iodine is completely changed to iodide. A1.1 g sample of copper ore is dissolved and Cu^(2+) (aq). is treated withKl . l_(2) liberated required 12.12" ml of " 0.1 MNa_(2)S_(2)O_(3) solution for titration . The % of Cu in the ore is

Free iodine is titrated against standard reducing agent usuallywith so

1.	Free iodine is titrated against standard reducing agent usuallywith sodium thiosulphate , i.e. K_(2)Cr_(2)O_(7) + 6Kl + 7H_(2)SO_(4) to Cr_(2)(SO_(4))_(3) + 4K_(2) SO_(4) + 7H_(2)O+l_(2) 2CuSO_(4) + 4Kl to Cu_(2)l_(2) + 2K_(2)SO_(4) + l_(2) l_(2) + Na_(2)S_(2)O_(3) to 2Nal + Na_(2)S_(4)O_(6) In iodometric titration, starch solution is used as an indicator. Starch solution gives blue or violet colour with free iodine .At the end point , blue or violet colour disappears when iodine is completely changed to iodide. A1.1 g sample of copper ore is dissolved and Cu^(2+) (aq). is treated withKl . l_(2) liberated required 12.12" ml of " 0.1 MNa_(2)S_(2)O_(3) solution for titration . The % of Cu in the ore is
Answer» `2.5%` `7%` `5.8%` `4.2%` SOLUTION :N/A