A wave of infrared light has a speed of 6 m/s and a wavelength of 12 m. what is the frequency of this wave?

The answer would be A

Note:

v = fλ

6 m/s = f * 12m

f = 6/12

f = 0.50 s⁻¹

f = 0.50 Hertz.

Note this was solved just for solving of it, infrared light is an electromagnetic wave and its speed cannot be 6m/s.

All electromagnetic wave infrared light inclusive would have a speed of ≈ 3 * 10⁸ m/s.