Testable questions: How will the grass growth rate affect the rabbits? Questions:
what is the manipulated variable, responding variable and the constant?

the manipulated variable is the growth rate of the grass, or the amount of food the rabbits have. the responding variable is the rabbits themselves. the constant is everything else in the scenario. the environment, the predators, etc.

yes its like the dead sea which is full of salt which makes you stay afloat

so yes an egg will float in salt

b. the carbon cycle ensures living things have a source of hydrogen