Question

identify the atom that increases in oxidation number in this redox reaction: 2mno2 + 2k2co3 =o2-->2kmno4+2co2

a. o
b. k
c. c
d. mn

Answer 1

When an atom increase in oxidation number, it is being oxidized (it is also the reducing agent.)
Looking at the charges on the metals
Mn goes from +4 to +7 .. so it is being oxidized because it loses electrons.
K goes from +2 to +1 so it is being reduced because it gains electrons.