Corrosion Questions in English

(B) Corrosion is the gradual destruction of materials (usually metals) by chemical or electrochemical reaction with their environment.
It is important to stop corrosion because:
$1$. It causes significant economic loss due to the replacement of damaged structures like bridges,buildings,and pipelines.
$2$. It compromises the structural integrity of metals,leading to potential safety hazards and failures.
$3$. It reduces the lifespan and efficiency of machinery and equipment.

(N/A) Corrosion of iron $(Fe)$ is an electrochemical process that acts like a galvanic cell.
$1$. At the anodic site,iron atoms lose electrons to form $Fe^{2+}$ ions: $2Fe(s) \rightarrow 2Fe^{2+}(aq) + 4e^-$.
$2$. At the cathodic site,oxygen and water react with the electrons released by iron to form hydroxide ions: $O_2(g) + 2H_2O(l) + 4e^- \rightarrow 4OH^-(aq)$.
$3$. The $Fe^{2+}$ ions further react with oxygen to form hydrated ferric oxide $(Fe_2O_3 \cdot xH_2O)$,which is known as rust.
$4$. The overall reaction is: $2Fe(s) + O_2(g) + 4H^+(aq) \rightarrow 2Fe^{2+}(aq) + 2H_2O(l)$.

(A) The correct answer is $A$. Rusting of iron is an electrochemical process. Iron is more reactive than tin. If the tin coating is peeled off,the iron is exposed to the atmosphere and acts as an anode,while the remaining tin acts as a cathode. This leads to the formation of a galvanic cell,which accelerates the corrosion of iron rather than preventing it. Therefore,the statement in option $A$ is incorrect.

(D) Statement $I$: Corrosion is an electrochemical process where the metal surface acts as an anode (undergoing oxidation) and the impurities or cathodic regions act as cathodes. This statement is correct.
Statement $II$: Corrosion,particularly the rusting of iron,is significantly accelerated in an acidic medium because the presence of $H^+$ ions facilitates the reduction reaction. In an alkaline medium,the rate of corrosion is generally lower. Therefore,Statement $II$ is false.
Conclusion: Statement $I$ is true,but Statement $II$ is false.

(B) Galvanization is the process of applying a protective $Zn$ coating to iron or steel to prevent rusting.
Because $Zn$ is more reactive than $Fe$,it gets oxidized first when it comes in contact with moisture,thereby acting as a sacrificial anode and protecting the iron surface from corrosion.

(A) Galvanization is the process of applying a protective $Zn$ (zinc) coating to iron or steel to prevent rusting.
Therefore,galvanized iron is coated with $Zn$ metal.

(A) When an iron rod is exposed to a moist atmosphere,it undergoes corrosion,commonly known as rusting.
This process involves the formation of hydrated ferric oxide $(Fe_2O_3 \cdot xH_2O)$ on the surface of the iron.
Since this involves the formation of chemical bonds between the iron surface and the oxygen/water molecules,it is classified as a surface phenomenon known as chemisorption.