3. Which element is most important for growing crops?
a. carbon dioxide
BA
b. hydrogen
C. calcium
d. nitrogen
4. Who discovered how to manipulate equilibrium systems?

B. hydrogen

Explanation:

that's because hydrogen is an element.

coral.

explanation:

coral. many marine organisms that produce calcium carbonate shells or skeletons are negatively impacted by increasing co2 levels and decreasing ph in seawater.

air

in a tire you fill a tire with air

then a couple days later you check the air pressure in the tire

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