What is the ppm concentration of Ca in a freshwater sample that contains 5.4 x 10^-6 M CaCo3.

Nonpoint source pollution is difficult to control because it

Draw the lewis dot structure for each of the following polyatomic ions

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?