Which reaction occurs at the cathode in an electrochemical cell? A. Cu(s) → Cu2+(aq) + 2e
B. Cu2+(aq) + H2(g) → Cu(s) + 2H+(aq)
C. Cu(s) + 2H+(aq) → Cu2+(aq) + H2(g)
D. Cu2+(aq) + 2e → Cu(s)

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 .

The volume of an unknown substance in a sealed glass jar is 50 milliliters. the volume of the jar is 200 milliliters. which state of matter could the substance be?

Determine the mass of the object below with accuracy and to the correct degree of precision. a. 324.2 g b. 324 g c. 324.30 g d. 324.25 g