| 1. | Pressure | 2. | Density of gas |
| 3. | Above both | 4. | None of the above |
| 1. | they are moving in the opposite direction. |
| 2. | the phase between them is \(90^{\circ}\). |
| 3. | the phase between them is \(45^{\circ}\). |
| 4. | the phase between them is \(0^{\circ}\). |
| 1. | \(502\) | 2. | \(507\) |
| 3. | \(517\) | 4. | \(522\) |
| 1. | \(1:2\) | 2. | \(2:3\) |
| 3. | \(3:4\) | 4. | \(4:5\) |