7th Class Science Physical and Chemical Changes Question Bank Physical and Chemical Changes

  • question_answer
    During the science activity, Ms Prabha demonstrated an experiment in following steps:
    Step 1: She burned a substance X over the candle flame and white dazzling light was observed. Also white powdery ash was left behind.
    Step 2:  She mixed the white ash formed with small amount of water. Then she dipped red and blue litmus papers into the solution one by one.
    Which of the following observations are correct?
    I. The substance burned in step 1 was magnesium.
    II. The white ash formed in step 1 was magnesium oxide.
    III. The solution formed in step 2 was acidic in nature
    IV. The solution formed in step 2 turned blue litmus red.

    A)  I and II only

    B)  III and IV only

    C)  I, II and III only

    D)  II, III and IV only

    Correct Answer: A


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