MnO2 + 4 HCl --> MnCl2 + 2 H2O + Cl2
identify d substance oxidised,substance reduced,oxidizing agent nd reducing agent...
MnO2 + 4HCl → MnCl2 + Cl2 + 2H2O
Here, Mn is in +4 oxidation state in MnO2 while it is in +2 Oxidation state in MnCl2 , thus a decrease in oxidation no. shows that MnO2 undergo reduction, and so it will work as an oxidizing agent.
Similarly, in HCl, Chlorine is in -1 oxidation state while it becomes 0 in Cl2 , the increase in oxidation no. shows that HCl undergoes oxidation and so it will act as a reducing agent.