There is no image or choices so what exactly do you want us to answer.
I think C, correct me if I’m wrong.
Answer:
b. cladophora
Explanation:
The cladophora algae is a type of green algae that grows attached to rocks or wood that are underwater. It forms short, rigid green filaments that branch, it's smell is similar to mushrooms. The cladophora is introduced in aquariums via contaminated plants or equipment, therefore to prevent it's formation it is necessary to clean everything before intoruducing it to the aquearium. This algae is so resistant once installed that usually the tank has to be re-started.
Answer: 0.04metres
Explanation:
The wavelength of a wave is the distance covered by the wave after one complete cycle. It is measured in metres, and represented by the symbol λ
Recall that Velocity (V) = Frequency F x wavelength λ
V = F λ
Make λ the subject formula
λ = V / F
In this case Frequency = 0.4 kHz
Convert kilohertz to hertz by multiplying 0.4 by 1000 i.e (0.4 x 1000Hz) = 400Hz
Velocity of wave = 16 m/s
So, λ = V / F
λ = 16 m/s / 400Hz
λ = 0.04metres
Thus, the wavelength of a wave is 0.04metres