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Question:

Read the following statements: I. When a red litmus paper is dipped into the reaction mixture of a saponification reaction, it turns blue and the reaction is exothermic. II. When a blue litmus paper is dipped into the reaction mixture of a saponification reaction, its color does not change and the reaction is exothermic. III. When a red litmus paper is dipped into the reaction mixture of a saponification reaction, its color does not change and the reaction is endothermic. IV. When a blue litmus paper is dipped into the reaction mixture of a saponification reaction, its color does not change and the reaction is endothermic. Which of the above statements are correct?

II and III

III and IV

I and II

I and IV

Solution:

The saponification reaction is exothermic in nature, because heat is liberated during the process. It is an alkaline hydrolysis process and the soap solution is basic and hence, turns red litmus paper blue whereas there is no effect on blue litmus paper. Option I is correct because the reaction is exothermic and the solution is basic, turning red litmus blue. Option II is also correct because the reaction is exothermic and the solution is basic, meaning blue litmus paper will not change color. Therefore, Option I and II are correct.