how much of a sample remains after three half-lives have occurred?
1/16 of the original sample
1/9 of the original sample
18 of the original sample
1/3 of the original sample

Apush or pull that moves or changes and object when to objects touch

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 .

Is 343 in the sequence -5, -2, 1, 4, 7