An aircraft is flying in an atmosphere of 30°C with a speed of 1260 km ph. Its speed is known as

ANS:B - sonic

Speed of aircraft:- A hypersonic speed exceeds 5 times the speed of sound, often stated as starting at speeds of Mach 5 and above. Supersonic speed is the speed of an aircraft that exceeds the speed of sound (Mach 1).

Sonic speed is the speed of an object that is equal to the speed of sound (Mach 1). Subsonic speed is the speed of an aircraft that less than the speed of sound (Mach 1). For objects traveling in dry air at a temperature of 0 °C(32 °F) at sea level, this speed is approximately 344 m/s (1238.40 km/hr).