JEE Main levelSingle correct optionDifficulty 2 of 3el043
Assertion (A): Sodium dodecylbenzenesulphonate can clean in hard water. Reason (R): The calcium and magnesium salts of dodecylbenzenesulphonic acid are insoluble and form scum. 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: C
A is true: the calcium and magnesium salts of alkylbenzenesulphonates are soluble in water, so no scum forms and cleaning continues. R is false because it claims these salts are insoluble.