NEET Practice Questions (MCQs) with Answers & Solutions

A redox reaction is a chemical reaction involving the transfer of electrons between reactants, causing changes in their oxidation states. In the given option, 2Na₂S₂O₃ + I₂ → Na₂S₄O₆ + 2NaI, sodium thiosulfate (Na₂S₂O₃) is oxidized by iodine (I₂) to form sodium tetrathionate (Na₂S₄O₆) and sodium iodide (NaI). This involves a transfer of electrons, making it a redox reaction.

Molecular weight of MCl_x

80 = x(4.5 + 35.5)

80 = 40x

x=2

Atomic weight = Equivalent weight x Valency.

= 4.5 x 2 = 9

A²⁺ $\to$A⁺⁴ + 2e^- x 3

3e^- + B³⁺ $\to$B x 2

Total no. of e^- transfered = 6

Intramolecular redox change involve oxidation of one atom and reduction of one atom within a molecule.

H₂0      : O.S. of oxygen = -2

O₂F_{2      :} O.S. of oxygen = +1

Na₂O    : O.S. of oxygen = -2

BaO_{2     :} O.S. of oxygen = -1

Balanced reaction

C₂H₅OH + 4I₂ + 6OH^- $\to$CHI₃ + HCO₂^- +5I^- + 5H₂O

Fe3+ (iron in +3 oxidation state), NO3- (nitrate ion), and SO3 (sulfur trioxide) can act as oxidants by accepting electrons from other species. An oxidant is a substance that oxidizes another substance by removing electrons from it.

In the molecule CH2=CCl2, one carbon atom is in the +2 oxidation state due to the double bond, while the other carbon atom is in the -2 oxidation state due to the two chlorine atoms attached to it. The average oxidation state of carbon is zero.