A substance has a percent composition of 17.55% Sodium, 39.70% Chromium, and 42.75% Oxygen. What is the empirical formula of the
substance? *

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The bond energy for the van der waals bond between two helium atoms is 7.9×10−4ev. assuming that the average kinetic energy of a helium atom is (3/2)kbt, at what temperature is the average kinetic energy equal to the bond energy between two helium atoms

Which of the following are sources of revenue for media companies? a. direct sales to producers b.advertising and subscriptions c. online purchase d. capital investments

Which of the four hypothetical substances you investigated would be most harmful to living organisms? 50 points!