Methyl orange is yellow and phenolphthalein is pink in a solution. Which ion is likely to be in excess?
Answer and explanation
Correct answer: Hydroxide ion
Phenolphthalein is pink in a basic medium and colourless in an acidic or neutral medium. Methyl orange is yellow in a neutral or basic medium, so the two observations together indicate that the solution is basic. In a basic aqueous solution, hydroxide ions are present in excess relative to hydrogen ions. Chloride and sulphate ions do not determine this indicator combination. Therefore option B is correct.
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What is the correct answer to this question?
Hydroxide ion
Why is this the correct answer?
Phenolphthalein is pink in a basic medium and colourless in an acidic or neutral medium. Methyl orange is yellow in a neutral or basic medium, so the two observations together indicate that the solution is basic. In a basic aqueous solution, hydroxide ions are present in excess relative to hydrogen ions. Chloride and sulphate ions do not determine this indicator combination. Therefore option B is correct.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
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