The 1st one. Fertilizers are like food for plants, and that's what an algae is, sorta. Trout's don't eat algae and if there's too much algae around, it gets dirty and they eventually die because of the amount of bacteria in the algae. It's the same thing if you have a fish tank.
Answer:
Wavelength, 
Explanation:
Given that,
Frequency, 
We need to find the wavelength of a photon of light. The relation between frequency and wavelength is as follows :

So, the wavelength of the light is
.
Answer:
The gain in mass by the negative electrode is the same as the loss in mass by the positive electrode. So the copper deposited on the negative electrode must be the same copper ions that are lost from the positive electrode.
Answer:
Radium
Explanation:
It has the highest atomic number so it would have more shells, making it larger than the others.