Which of the following is NOT likely to cause a change in average annual temperatures on Earth? ​a. Human activity. b. Solar eclipses.
​c. Photosynthesis by plants and algae. ​d. Strength of solar radiation.

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.