A. Redox reaction occurs during passivation, and dense oxide is generated to prevent further reaction, so the iron container can hold cold concentrated sulfuric acid, so A is wrong;

B. The aluminothermic reaction is exothermic, but it needs to provide a certain amount of energy to initiate the reaction, so B is wrong;

C. Increasing the height of blast furnace has no effect on the chemical balance, so the conversion rate of co cannot be improved, so C is correct;

D lead acetate is a heavy metal salt, which can denature protein. Then add two drops of 1% lead acetate solution to egg white to produce precipitation, so d is wrong;

So choose C.