Answer :

To determine the correct chemical formula for diphosphorus pentoxide, let's break down the name:

1. "Diphosphorus" indicates the presence of two phosphorus (P) atoms. The prefix "di-" means two.
2. "Pentoxide" indicates the presence of five oxygen (O) atoms. The prefix "penta-" means five.

Combining these insights:

- We have two phosphorus atoms: \( \text{P}_2 \)
- We have five oxygen atoms: \( \text{O}_5 \)

Therefore, the chemical formula for diphosphorus pentoxide is \( \text{P}_2\text{O}_5 \).

Now, let's match this formula to the given choices:

A. \( \text{PO}_5 \) – This is incorrect because it specifies one phosphorus atom and five oxygen atoms.

B. \( \text{P}_2\text{O}_5 \) – This is correct as it specifies two phosphorus atoms and five oxygen atoms.

C. \( \text{P}_5\text{O} \) – This is incorrect because it specifies five phosphorus atoms and one oxygen atom.

D. \( \text{P}_5\text{O}_2 \) – This is incorrect because it specifies five phosphorus atoms and two oxygen atoms.

Thus, the correct choice is:
B. [tex]\( \text{P}_2\text{O}_5 \)[/tex]