MCQ
Iron becomes passive by ..................... due to formation of .....................
- Adil. $HCl, Fe_2O_3$
- ✓$80\%$ conc. $HNO_3, Fe_3O_4$
- Cconc. $H_2SO_4, Fe_3O_4$
- Dconc. $HCl, Fe_3O_4$
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$(A)\,\,NH_4OH + NH_4Cl$ $(B)\,\,HCl + NaCl$
$(C)\,\,NH_4OH + HCl$ in $2 : 1\,mole$ ratio
Select the correct answer using the code given below
$(I) \,S _{2} O _{4}^{2-}$
$(I I)\, S _{2} O _{5}^{2-}$
$(III) \,S _{2} O _{6}^{2-}$