(i) the number of conduction electrons in a sample of pure semiconductor is `7xx10^(20)` per cubic metre calculate the number of holes in a sample of size `2cm xx2 cm xx2 cm`
(ii) an electron in the conduction band combines with a hole in the valence band of the semiconductor and excess energy is released in the of the semiconductor is 2.1 eV find the maximum wavelength that can be emitte in this process

Explanation

### Step-by-Step Solution

#### Part (i): Calculate the number of holes in the semiconductor sample

1. **Identify the given data:**
- Concentration of conduction electrons (n) = \(7 \times 10^{20} \, \text{m}^{-3}\)
- Size of the sample = \(2 \, \text{cm} \times 2 \, \text{cm} \times 2 \, \text{cm}\)

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