Which development in human history first made waste disposal a problem? a. decrease in birth rate b. growth of cities c. increase in agriculture d. new diseases

When balancing a chemical equation:

What was bohr’s contribution to the planetary model

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.