Why is it important to test only one variables during an experiment?

Andesitic rocks have mineral compositions between those of and basaltic rocks. a. conglomerate c. granitic b. metamorphic d. organic select the best answer from the choices provided a b c d i need asap

Which of the following represents the chemical reaction of hydrazine and hydrogen peroxide to produce nitrogen and water? a. nitrogen + hydrogen peroxide → hydrazine + water b. nitrogen + water → hydrazine + hydrogen peroxide c. hydrazine + hydrogen peroxide → nitrogen + water d. water + hydrogen peroxide → nitrogen + hydrazine

!if we removed the wolf, snake, and hawk from this food web, what best explains the impact it would have? a) the number of producers would increase. b)the number of decomposers would increase. c)the number of primary consumers would increase. d)the numbers of primary consumers would decrease.