15-Which of the following(s) is hare comest? 1. In Ina-Exchange separation technique negatively- chargedices of the solution attached on cation exchange resin 11-A substance that affects an analytical signal or the background is called an interference. III.As the occentration of solute which remains in aqueous solution decreases extraction efficiency increases. A) Only I B) Only I C) I and II D) I and III E) II and III

The correct answer is C) I and II.<br /><br />Explanation:<br /><br />I. In ion-exchange separation, negatively-charged ions of the solution are attached to the cation exchange resin. This is correct.<br /><br />II. A substance that affects an analytical signal or the background is called an interference. This is also correct.<br /><br />III. As the concentration of solute which remains in aqueous solution decreases, extraction efficiency increases. This statement is incorrect. The correct statement would be: As the concentration of solute which remains in aqueous solution increases, extraction efficiency decreases.<br /><br />Therefore, the correct answer is C) I and II.