Lead pipes are readily corroded by:
A) Water
B) Acetic acid
C) Conc. H₂SO₄
D) Dil. H₂SO₄

Lead (Pb) is a metal that is known to be relatively resistant to corrosion in dry air but can be corroded by certain chemicals. Let’s analyze each option to determine which can readily corrode lead pipes.

### A) Water
Lead can react with pure water in the presence of oxygen to form lead hydroxide, but this process is slow and forms a protective layer on the surface of the lead. So, water alone doesn't corrode lead pipes readily.

### B) Acetic acid
Acetic acid is an organic acid, and it reacts with lead quite readily. The reaction between lead and acetic acid produces lead acetate, which is soluble in water. Thus, lead pipes can be easily corroded by acetic acid.

\[
\text{Pb} + 2 \, \text{CH}_3\text{COOH} \rightarrow (\text{CH}_3\text{COO})_2\text{Pb} + \text{H}_2
\]
Lead acetate is toxic and leads to contamination of liquids in contact with corroded lead.

### C) Concentrated \(\text{H}_2\text{SO}_4\) (Sulfuric acid)
Lead is resistant to concentrated sulfuric acid due to the formation of an insoluble layer of lead sulfate on the surface, which prevents further corrosion.

### D) Dilute \(\text{H}_2\text{SO}_4\)
Dilute sulfuric acid reacts with lead to form soluble lead sulfate and hydrogen gas. This reaction can cause corrosion of lead pipes.

\[
\text{Pb} + \text{H}_2\text{SO}_4 \rightarrow \text{PbSO}_4 + \text{H}_2
\]

### Conclusion:
The correct answer is **B) Acetic acid**, as it readily corrodes lead pipes by forming soluble lead acetate.