The question asks for the classical, oxygen-based definition of oxidation. We need to recall the traditional definitions of oxidation and reduction in terms of oxygen and hydrogen transfer.
A) Gains oxygen (or, equivalently, loses hydrogen) — This option correctly states the classical definition of oxidation, which involves either the gain of oxygen or the loss of hydrogen.
The question asks for the classical, oxygen-based definition of reduction. This definition predates the more modern electron-transfer definition and focuses on the gain or loss of oxygen and hydrogen atoms.
A) Loses oxygen (or, equivalently, gains hydrogen)
This option correctly defines reduction according to the classical, oxygen-based perspective. Reduction is the removal of oxygen or the addition of hydrogen to a substance.
To determine which substance is oxidized in a redox reaction, we need to recall the definitions of oxidation and reduction. Oxidation can be defined as the gain of oxygen, the loss of hydrogen, or the loss of electrons. Reduction is the opposite: loss of oxygen, gain of hydrogen, or gain of electrons.
\[ \text{CuO} + \text{H}_2 \xrightarrow{\text{heating}} \text{Cu} + \text{H}_2\text{O} \]
B) Hydrogen (Hâ‚‚), since it gains oxygen to form water
This option correctly identifies hydrogen as the substance that is oxidized because it gains oxygen to form water (\(\text{H}_2\text{O}\)).
To identify the reducing agent in a redox reaction, we need to determine which substance undergoes oxidation. Oxidation is defined as the loss of electrons, gain of oxygen, or loss of hydrogen. Conversely, reduction is the gain of electrons, loss of oxygen, or gain of hydrogen. A reducing agent is the substance that gets oxidized and causes the reduction of another substance.
Correct Option: B) Hydrogen (Hâ‚‚) is the reducing agent because it undergoes oxidation (loses electrons/gains oxygen) by changing its oxidation state from \(0\) to \(+1\), thereby reducing Copper(II) oxide.
To identify the oxidising agent, we need to understand the definitions of oxidation and reduction in terms of oxygen transfer or change in oxidation states. An oxidising agent is the substance that causes oxidation in another substance by undergoing reduction itself.
B) Copper(II) oxide (CuO) is the correct answer because it loses oxygen (undergoes reduction) and thus causes the oxidation of hydrogen.
The question asks for the modern, electron-transfer-based definition of oxidation. Oxidation and reduction are fundamental concepts in chemistry, particularly in redox reactions. Understanding these definitions is crucial for competitive exams.
B) Loses one or more electrons — This is the correct modern definition of oxidation. When a substance loses electrons, its oxidation state increases. For example, in the reaction \( \text{Na} \rightarrow \text{Na}^+ + \text{e}^- \), sodium loses an electron and is oxidized.