Star 1 is 18 light years from Star 2 and 34 light years from Earth. If Star 2 explodes as a supernova, in how many years would the explosion be seen from Earth?

What is the mass of 8 moles of sodium atoms

Chlorophyll a had the molecular formula c55h72mgn4o5 how many atoms are in this molecule

Nitric acid can be formed in two steps from the atmospheric gases nitrogen and oxygen, plus hydrogen prepared by reforming natural gas. in the first step, nitrogen and hydrogen react to form ammonia: (g) (g) (g) in the second step, ammonia and oxygen react to form nitric acid and water: (g) (g) (g) (g) calculate the net change in enthalpy for the formation of one mole of nitric acid from nitrogen, hydrogen and oxygen from these reactions. round your answer to the nearest .