Consider the reaction, MnO2+4HCl→MnCl2+2H2O+Cl2; In this reaction two moles of HCl reduces ‘X’ moles of MnO2 .  Value of  ‘X’ is

MnO2+4HCl→MnCl2+2H2O+Cl2; 1 mole of MnO2 reacts with 4 moles of HCl; Of the 4 moles of HCl, only two moles are oxidized to Cl2 by one mole of MnO2Alternate method: Criss-cross :1 mole of MnO2 oxidizes 2 moles of HCl