Which of the following reactions shows a chemical change producing a gas? A. H2(g) + O2(g) → H20(1)
B. 2CH2OH() + 302(9) ► 2002(g) + 4H20(1)
C. NaCl(s) → NaCl(aq)
D. 2AgNO3(aq) + CaBr2(aq) → 2AgBr(s) + Ca(NO3)2(aq)

Consider the reduction reactions and their equilibrium constants. cu+(aq)+e−↽−−⇀cu(s)pb2+(aq)+2e−↽−−⇀pb(s)fe3+(aq)+3e−↽−−⇀fe(=6.2×108=4.0×10−5=9.3×10−3 cu + ( aq ) + e − ↽ − − ⇀ cu ( s ) k =6.2× 10 8 pb 2 + ( aq ) +2 e − ↽ − − ⇀ pb ( s ) k =4.0× 10 − 5 fe 3 + ( aq ) +3 e − ↽ − − ⇀ fe ( s ) k =9.3× 10 − 3 arrange these ions from strongest to weakest oxidizing agent.