Sound waves travel at 340 m/s through warm air and at 3400 m/s through brass. The wavelength of a 700 Hz acoustic wave as it enters brass from warm air:
Decrease by a factor 20
Decrease by a factor 10
Increases by a factor 20
Increases by a factor 10
Here,
When a sound wave travels from one medium to another medium its frequency remains the same
Since f remains the same in both the medium