What is the frequency of an electromagnetic wave that has a wavelength of 300,000 km? (the speed of light is 300,000 km/

Frequency represents the number of complete oscillations in one second. it is measured in Hertz (Hz). Electromagnetic waves are waves which do not require a material media for transmission. They travel with a speed of light.
The speed (m/s) of a wave is given by  frequency (Hz) × Wavelength (m)
Speed is 300,000 km/sec or 300,000,000 m/s and the wavelength is 300,000  km or 300,000,000 m.
Frequency = speed÷ wavelength
                 = 300000000 ÷ 300000000 = 1
Therefore, the frequency of the wave is 1Hz

The correct answer is: a

Amethod of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.