JEE Advanced levelSingle correct optionDifficulty 3 of 3el050
Assertion (A): An aqueous solution of sodium stearate turns red litmus blue. Reason (R): The stearate ion is the conjugate base of a weak acid and is partly hydrolysed to give OHX− ions. Choose the correct option.
ABoth A and R are true and R is the correct explanation of A
BBoth A and R are true but R is not the correct explanation of A
CA is true but R is false
DA is false but R is true
Answer: A
Stearic acid is a weak acid, so the stearate ion reacts with water, CX17HX35COOX−+HX2OCX17HX35COOH+OHX−, producing hydroxide. The solution is basic and turns red litmus blue, so R explains A.