Which of the following can astronomers detect if a star is a part of a binary system
(a) the star varies in temperature near the binary
(b)the star wobbles near the binary star
(c)the star has very strong gravity
(d) the star belongs to an open cluster

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 .