Which of the following is not a redox reaction?

Options

A. `CaCO_(3)rarrCaO+CO_(2)`
B. `O_(2)+2H_(2)rarr2H_(2)O`
C. `Na+H_(2)OrarrNaOH+(1)/(2)H_(2)`
D. `MnCl_(3)rarrMnCl_(2)+(1//2)Cl_(2)`

Answer

A

Explanation

a. Oxidation states of `Ca` and `C` are `+2` and `+4`, respectively, in both reactant and product , hence, not redox.
b. `{:(4e^(-)+,O_(2)rarr2O^(2-)("Reduction"),,,),(H_(2)+,2H^(o+)+2e^(-)("Oxidation"),,,):}`
Hence, redox.
c. `{:(Na,rarrNa^(o+)+e^(-)("Oxidation"),,,),(2H^(o+)+2e^(-),rarrH_(2)( "Reduction"),,,):}`
Hence redox.
d. `{:(e^(-)+Mn^(3+)rarrMn^(2+),("Reduction"),,,),(2Cl^(ө)rarrCl_(2)+2e^(-),("Oxidation"),,,):}`
Hence, redox.