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Subject :NSO    Class : Class 9

The given graph represents the cooling curve of substance X. Which of the following statements are incorrect?

I. Process I represents cooling of liquid state of X while process III involves cooling of the solid state.
II. The freezing point of substance X is 25 °C.
III. At 35 °C, the substance exists in solid state.
IV. Substance X exists both in gaseous and liquid form along the curve QR.

AI and III only
BII and IV only
CIII and IV only
DNone of these

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