7th Class Science Acids, Bases and Salts Question Bank Acids, Bases and Salts

  • question_answer 80) Following observation were recorded upon performing experiments with sample 'A' and sample 'B'. (i) When 2-3 drops of phenolphthalein are added to sample 'A' it becomes pink. (ii) When equal quantities of two samples are added in a test-tube, the test-tube becomes hot.

    A) sample 'A' is basic      

    B) sample 'B' is acidic

    C) (ii) observation confirms neutralisation

    D) All the above are correct

    Correct Answer: D

    Solution :

    Phenolphthalein gives a pink colour with basic solution so sample 'A' is basic. Sample 'A' and 'B' react to give neutralization reaction which is exothermic (evolution of heat) so solution 'B' is acidic.

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