Which of the following statements is true? * O Hormones are usually needed in large amounts. Hormones are usually needed in small amounts. Hormones are carried by the respiratory system. Hormones are produced by the nervous system.​

Hormones are usually needed in large amounts - False

Hormones are usually needed in small amounts. - True

Hormones are carried by the respiratory system. - True

Hormones are produced by the nervous system.​ - True

answer: 21

step-by-step explanation:

divide 630 by 30. 30 goes into 630 21 times

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%