Turmeric turns reddish-brown and red litmus turns blue in a solution. Which ion is likely to be in excess?

Correct answer: Hydroxide ion

Both observations indicate a basic medium. Turmeric changes to a reddish-brown colour in the presence of a base, and red litmus turns blue when the solution is basic. In the Arrhenius description, basicity in aqueous solution is associated with an excess of hydroxide ions, OH⁻, relative to hydrogen ions. Chloride and sulphate ions may be present in salts but do not alone explain these indicator changes. Therefore option B is correct.