Which one of the following statements about the speed of sound waves is not correct?

The speed of sound is determined by the properties of the medium through which it travels. Sound is a mechanical wave that travels faster in solids than in liquids, and faster in liquids than in gases [1]. Consequently, the speed of sound in steel (solid) is higher than in water (liquid), and the speed in water is higher than in air (gas). Regarding temperature, the speed of sound in air is directly proportional to the square root of its absolute temperature. As temperature increases, the kinetic energy of the molecules increases, allowing them to vibrate and transmit disturbances more quickly. Data shows that sound travels at approximately 331 m/s at 0°C and increases to about 343 m/s at 20°C. Therefore, the statement that the speed of sound in air decreases with an increase in temperature is incorrect.

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > Primary Waves (P-Waves) > p. 60