Identify at least one example each of absorption, transmission, reflection and refraction of waves in this photograph

Use the periodic table to determine the electron configuration of dysprosium (dy) and americium (am) in noble-gas notation.

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.

Ab c or d ? i’m not sure what the answer is