Silver Reaction: Understanding Tarnishing

Silver (Ag) typically turns black due to a chemical reaction with substances containing sulfur in the environment. The most common cause is hydrogen sulfide ($H_2S$), a gas present in the air.

Chemical Reaction Explanation

The reaction forms silver sulfide ($Ag_2S$), a black compound, on the surface of the silver.

The simplified reaction is:

$2Ag + H_2S \rightarrow Ag_2S (black) + H_2$

Analysis of Options

• Sulphur (Option D): Sulphur compounds, like $H_2S$, directly react with silver to cause tarnishing. This aligns with the observed phenomenon.
• Carbon (Option A): Carbon does not typically react with silver under normal conditions to cause blackening.
• Zinc (Option B): Zinc is a reactive metal but does not cause silver to turn black through direct reaction in this manner.
• Magnesium (Option C): Magnesium is also reactive, but it does not cause silver tarnishing.

Therefore, sulfur is the substance responsible for silver turning black.