Lead is only slightly attacked dilute hydrochloric acid , because

Options

A. Pb is less electropositive than hydrogen
B. `PbO_2` film is always present on Pb, which resists chemical attack
C. PbO film is formed , which resists chemical attack by acid
D. a protective coating of `PbCl_2` is formed on the Pb surface

Answer

To solve the question "Lead is only slightly attacked by dilute hydrochloric acid, because...", we need to understand the behavior of lead when it comes into contact with dilute hydrochloric acid (HCl). Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Chemical Behavior of Lead
Lead (Pb) is a metal that can react with acids. However, its reactivity with dilute hydrochloric acid is limited.

**Hint:** Consider the properties of lead and how it interacts with acids.

### Step 2: Understand the Reaction with Dilute HCl
When lead is exposed to dilute hydrochloric acid, it does react, but the reaction is not vigorous. The lead reacts to form lead(II) chloride (PbCl2).

**Hint:** Think about what products are formed when metals react with acids.

### Step 3: Formation of an Insoluble Crust
The lead(II) chloride (PbCl2) that forms is not soluble in water. This leads to the formation of a protective crust on the surface of the lead.

**Hint:** Reflect on the solubility of the products formed in the reaction.

### Step 4: Protective Coating
This crust of lead(II) chloride acts as a barrier, preventing further reaction between the lead and the hydrochloric acid. As a result, the lead is only slightly attacked by the acid.

**Hint:** Consider how protective layers can influence the reactivity of metals.

### Step 5: Conclusion
Therefore, the reason why lead is only slightly attacked by dilute hydrochloric acid is that it forms a protective coating of insoluble lead(II) chloride (PbCl2) on its surface, which limits further reaction.

**Final Answer:** Lead is only slightly attacked by dilute hydrochloric acid because a protective coating of insoluble lead(II) chloride (PbCl2) is formed on the lead surface.