Q.Deduce the oxidation number of oxygen in hypofluorous acid – HOF.

Step 1. Assign the fixed oxidation states.

Hydrogen is +1 (its usual value when bonded to a more electronegative element). Fluorine is always -1, being the most electronegative element of all, regardless of what else it is bonded to.

Step 2. Set up the neutrality equation.

HOF is a neutral molecule, so the sum of all oxidation numbers must equal zero: (+1) + x + (-1) = 0, where x is the oxidation number of oxygen.

Step 3. Solve for oxygen.

1 + x - 1 = 0, so x = 0.

Step 4. Rationalise the result. …

Apply the fixed oxidation-state rules for H (+1, bonded to a more electronegative atom) and F (always -1), then solve the over …

Assuming oxygen is 'always -2' regardless of context and applying that blindly to HOF, without recognising that fluorine's unique -1 assignment (it being mor …