IB Physics SL C 2 4 Nature of Electromagnetic Waves Topic Practice

This question is in two parts. Part 1 is about a thermistor circuit. Part 2 is about vibrations and waves.
Part 1 Thermistor circuit
The circuit shows a negative temperature coefficient (NTC) thermistor X and a $100 \mathrm{k} \Omega$ fixed resistor R connected across a battery.

The battery has an electromotive force (emf) of 12.0 V and negligible internal resistance.

The sound waves from the loudspeaker travel in air with speed $330 \mathrm{~m} \mathrm{~s}^{-1}$.

Describe the characteristics of sound waves in air.