The quantum yield for decomposition of HI id 0.2 .In an experiment 0.01 moles of HI are decomposed .
Find the number of photons absorbed.

Explanation

To solve the problem of finding the number of photons absorbed during the decomposition of HI, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Data:**
- Quantum yield (Φ) for the decomposition of HI = 0.2
- Moles of HI decomposed = 0.01 moles

2. **Calculate the Number of Molecules of HI:**
- Use Avogadro's number (approximately \(6.022 \times 10^{23}\) molecules/mole) to find the total number of HI molecules.
\[ \text{Number of molecules} = \text{Moles of HI} \times \text{Avogadro's number} \]
\[ \text{Number of molecules} = 0.01 \, \text{moles} \times 6.022 \times 10^{23} \, \text{molecules/mole} = 6.022 \times 10^{21} \, \text{molecules} \]

3. **Use the Quantum Yield to Find the Number of Photons Absorbed:**
- The quantum yield is defined as the ratio of the number of molecules decomposed to the number of photons absorbed:
\[ \Phi = \frac{\text{Molecules decomposed}}{\text{Photons absorbed}} \]
Rearranging this gives us:
\[ \text{Photons absorbed} = \frac{\text{Molecules decomposed}}{\Phi} \]
Substituting the values we have:
\[ \text{Photons absorbed} = \frac{6.022 \times 10^{21} \, \text{molecules}}{0.2} = 3.011 \times 10^{22} \, \text{photons} \]

4. **Final Answer:**
- The number of photons absorbed during the decomposition of HI is approximately \(3.011 \times 10^{22}\) photons.