Q1: Reduction reaction involves the

ANS:C - gain of electrons.

The gain of electrons refers to a chemical process in which an atom, ion, or molecule acquires one or more electrons from its surroundings. This process results in a decrease in the positive charge or an increase in the negative charge of the species involved. Here's a detailed explanation of the gain of electrons:

1. Electron Transfer:
   • Atoms, ions, or molecules undergo the gain of electrons through electron transfer reactions. During these reactions, one species donates electrons, while the other accepts them.
   • The species that accepts electrons is said to be reduced because it gains negatively charged electrons, thereby becoming more negatively charged itself.
2. Increase in Negative Charge:
   • By gaining electrons, a species increases its negative charge. Electrons are negatively charged particles, so acquiring additional electrons adds negative charge to the species.
   • For example, if an atom gains one electron, it becomes negatively charged by one unit. If it gains two electrons, its negative charge increases by two units, and so on.
3. Oxidation State Reduction:
   • The gain of electrons often corresponds to a decrease in the oxidation state (oxidation number) of the species involved.
   • For example, consider the reduction of oxygen gas (�2O2​) to form oxide ions (�2−O2−) in the following reaction: �2+4�−→2�2−O2​+4e−→2O2−
   • In this reaction, each oxygen molecule (�2O2​) gains four electrons (4�−4e−) to form two oxide ions (�2−O2−). This results in a decrease in the oxidation state of oxygen from 00 in �2O2​ to −2−2 in �2−O2−.
4. Role in Redox Reactions:
   • The gain of electrons is a key feature of reduction reactions, which are often paired with oxidation reactions in redox (reduction-oxidation) reactions.
   • In a redox reaction, one species undergoes reduction (gain of electrons) while another undergoes oxidation (loss of electrons). The transfer of electrons between the oxidized and reduced species drives the reaction.
5. Applications:
   • The gain of electrons is central to many biological, chemical, and electrochemical processes, including photosynthesis, respiration, corrosion, and battery operation.
   • Understanding and controlling electron transfer processes are crucial for manipulating chemical reactions and developing new technologies.

In summary, the gain of electrons is a fundamental process in which a species acquires electrons, leading to an increase in its negative charge and often a decrease in its oxidation state. This process plays a crucial role in redox reactions and has widespread applications in various fields of science and technology.