What is the atomic symbol for the alkaline earth metal that has 2 electron shells?

Areaction is first order with respect to reactant x and second order with respect to reactant y. which statement describes the rate law for this reaction?

Light waves travel than sound waves.

Which of the following statements is true about energy quantization at the atomic level? electrons in the outermost orbits are the most stable. electrons in all the orbits around the nucleus have the same amount of energy. electrons in the orbit closest to the nucleus have the least amount of energy. electrons absorb or release the same amount of energy independent of the energy levels.