What type of contraction is represented by each of the following events? options are either isotonic eccentric contraction or isotonic concentric contraction. a) a weight lifter puts a barbell back on the floor. b) a weigh lifter pulls a barbell up to his waist. c) a mother lowers an infant into his crib. d) a man pulls open a door for his date. e) a sprinter leaves the starting block.

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 .