Oxidation State Change in Nitrification

Steps:

• In NH₄⁺, oxidation number of N is -3: N + 4(+1) = +1, so N = -3.
• In NO₃⁻, oxidation number of N is +5: N + 3(-2) = -1, so N = +5.
• Change in oxidation number: +5 - (-3) = +8.

Why C is correct:

• The difference follows standard oxidation state rules for assigning numbers in ions, confirming +8 increase during nitrification.

Why the others are wrong:

• A: Indicates reduction, but process is oxidation.
• B: Underestimates difference by 2 from actual +8.
• D: Overestimates by 1, ignoring precise ion calculations.

Final answer: C