***50 points*** show all work. 1. what are the 2 methods of balancing redox reactions? 2. practice 8: which atom has a change in oxidation number of +4 in this redox reaction? k2cr2o7 (aq) + h2o (l) + s (s) → koh (aq) + cr2o3 (s) + so2 (g) 3. practice 9: which atom has a change in oxidation number of -3 in this redox reaction? k2cr2o7 (aq) + h2o (l) + s (s) → koh (aq) + cr2o3 (s) + so2 (g) 4. practice 10: balance this redox reaction using the oxidation-number change method and describe each step you used: hno2 (aq) + hi (aq) → no (g) + i2 (s) + h2o (l) 5. practice 11: balance this redox reaction using the oxidation-number change method and describe each step you used: hcl (aq) + zn (s) → zncl2 (s) + h2 (g) 6. do you know how to identify oxidation half-reaction and reduction half-reaction in a redox equation?