| 1. | \(4.77~ \mathring{A}\) | 2. | \(0.53~ \mathring{A}\) |
| 3. | \(1.06~ \mathring{A}\) | 4. | \(1.59~ \mathring{A}\) |
| 1. | \(13.6~\text{eV}\) | 2. | \(6.8~\text{eV}\) |
| 3. | \(1.51~\text{eV}\) | 4. | \(3.4~\text{eV}\) |
| 1. | visible region |
| 2. | far infrared region |
| 3. | ultraviolet region |
| 4. | infrared region |
| 1. | \(-1.5~\text{eV}\) | 2. | \(-1.6~\text{eV}\) |
| 3. | \(-1.3~\text{eV}\) | 4. | \(-1.4~\text{eV}\) |

| 1. | \( n_1 = 6~\text{and}~n_2 = 2\) | 2. | \( n_1 = 8~\text{and}~ n_2 = 1\) |
| 3. | \( n_1 = 8~\text{and}~ n_2 = 2\) | 4. | \(n_1 = 4~\text{and}~n_2 = 2\) |