Answer:
Option 1, Cl is reduced and gains electrons
Explanation:
HClO₃ → HClO₂
In HClO₃, chlorine acts with +5 in the oxidation state
In HClO₂,, chlorine acts with +3 in the oxidation state.
The state has been reducted, so the Cl has been reduced. As it was reduced, it means that has won e⁻, in this case 2
Cl⁻⁵ → Cl⁻³ + 2e⁻
Mass of electrons are not included when calculating the atomic mass of element. Atomic mass of the element is equal to proton + neurons. Example the the mass number of Nitrogen can be calculated as 7 protons + 7 neutrons to give 14 . thus nitrogen has a mass number of 14
