The speed of the sound

In air at 20°C, sound travels at about 343 m/s. How fast is that in km/h ?

In water, sound travels at 1450 m/s. How fast is that in km/h ?

The speed of hypersonic aircraft is expressed in Mach. The Mach number (M) is how many times faster than the speed of sound that the aircraft travels at. At the altitude the aircraft fly at, the speed of sound is about 293 m/s. How fast is 1 Mach in km/h ?

The experimental hypersonic aeroplane X-43A went at the record speed of 12,000km/h. What Mach speed is that closest to ?

Concorde was a supersonic plane, which flew at Mach 2. It flew from Paris to New York in 3 hours 26 minutes, of which 2 hours 54 minutes were 'supersonic'. 2 hours 54 minutes were 'supersonic'. How far, in kilometres, did the plane fly when it travelled at Mach 2 ?

round to the nearest whole number