Henry mixed salt and water together in a cup until he observed a clear solution. he measured the mass of the solution. then he placed the cup outside for several sunny days during the summer. after a week, he observed that only solid salt remained in the cup and the mass had decreased. henry concluded that a physical and chemical change occurred in this investigation. which statements correctly defend or dispute his conclusion? he is correct. dissolving salt in water is a physical change, but evaporating the water is a chemical change. formation of a solid is evidence that a chemical change occurred. he is correct. evaporation is a physical change, but dissolving salt in water is a chemical change. the change in mass is evidence that a chemical change occurred. he is incorrect. dissolving salt in water and evaporation of the water are both physical changes. the reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change. he is incorrect. dissolving salt in water and evaporation of the water are both chemical changes. the reappearance of salt is evidence that the change was reversible by a chemical change, so it could not be a physical change.

The peak wavelength for the blackbody curve of a star is in the uv range. assuming the radiation from this star can reach earth, would you be able to see it?

Astudent made a graph plotting the progress of a reaction over time. the student forgot to label the y-axis of the graph. a graph is shown with two graph lines. one graph line starts at a higher position on the y axis and slopes downwards towards the right. the other graph line starts at a lower position on the y axis and slopes upwards towards the right. the two graph lines stop short of intersecting each other and continue as separate lines which gradually become straight and parallel to the x axis. a vertical line is shown at a point where the two graph lines finally became parallel to the x axis. this vertical line is labeled equilibrium. the title on the x axis is time and an arrow pointing towards the right is shown above time. the title on the y axis is left blank. what best explains the label that the student should use on the y-axis? amount, because as the amount of product decreases, the amount of reactant increases over time. reaction rate, because forward and backward reaction become equal at equilibrium. amount, because the amounts of reactants and products become constant after equilibrium is reached. reaction rate, as the rate of forward reaction increases and rate of backward reaction decreases over time.

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