Sound Wave Front

Q. As a wave propagates,

1. The wave intensity remains constant for a plane wave.
2. The wave intensity decreases as the inverse of the distance from a line source.
3. The wave intensity decreases as the inverse square of the distance from a point source.
4. Total intensity of the spherical wave over the spherical surface centered at the source remains constant at all times

Q. If the source is moving towards right, wave-front of sound waves get modified to

1. 
2. 
3. 
4. None of these