7. (30pt) A long vertical tube is open at the top and contains a small orifice in its base, which is otherwise closed. The lower 10-m section of the tube is filled with carbon dioxide (MW = 44). Otherwise, there is nitrogen (MW = 28) above the carbon dioxide in the tube and also outside the tube. Calculate the velocity (m/s) of carbon dioxide that issues from the orifice. In which direction does it flow?

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