A chemical process in which there is a gain of electrons is known as?

Analysis

The question asks for the definition of a chemical process characterized by the gain of electrons. This is a fundamental concept in electrochemistry and redox (reduction-oxidation) reactions.

Concept Explanation

To understand this, we use the popular mnemonic OIL RIG:

• Oxidation Is Loss (of electrons)
• Reduction Is Gain (of electrons)

In any redox reaction, electrons are transferred from one species to another. The species that gains electrons undergoes a decrease in its oxidation state, which is defined as reduction. Conversely, the species that loses electrons undergoes an increase in its oxidation state, which is defined as oxidation.

Step-by-Step Solution

1. Evaluate Option A (Sublimation): This is a physical process where a solid changes directly into a gas without passing through the liquid phase. It does not involve electron transfer.
2. Evaluate Option B (Reduction): By definition, reduction is the gain of electrons. For example, in the reaction $Cl_2 + 2e^- \rightarrow 2Cl^-$, chlorine gains electrons and is reduced.
3. Evaluate Option C (Oxidation): By definition, oxidation is the loss of electrons. For example, in the reaction $Na \rightarrow Na^+ + e^-$, sodium loses an electron and is oxidized.
4. Evaluate Option D (Distillation): This is a physical process used to separate mixtures based on differences in boiling points. It does not involve electron transfer.

Since the question specifically asks for the process involving the gain of electrons, the correct term is reduction.

Exam Tip

Whenever you see a question about electron transfer, immediately write "OIL RIG" on your scratch paper. It is a foolproof way to ensure you don't mix up oxidation and reduction during the pressure of the exam.