Một chiếc đinh sắt cân nặng 6 gam. Bỏ chiếc đinh sắt vào nước đựng trong ống đong có chia vạch, mực nước dâng lên tương ứng với thể tích là 0.8cm3(khối) . biết rằng sắt có khối lượng riêng D=7,8g/cm3(khối).Hãy giải thích cho biết chiếc đinh làm bằng sắt có tinh khiết không ?

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