Question

question 33
which of the following groups of elements accounts for more than 95% of the human body by weight?
a carbon, hydrogen, oxygen, nitrogen
b calcium, hydrogen, oxygen, nitrogen
c carbon, phosphorus, oxygen, hydrogen
d calcium, phosphorus, hydrogen, nitrogen

question 34
a water solution that contains equal numbers of hydrogen ions and hydroxide ions is
a acidic
b basic
c alkaline
d neutral

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Explanation:

Question 33

The human body's major elements by weight (over 95%) are carbon, hydrogen, oxygen, and nitrogen. Calcium, phosphorus are minor or trace in terms of weight percentage here. So option A has the correct group.

In a solution, if $[\ce{H+}] = [\ce{OH-}]$, the solution is neutral. Acidic has more $\ce{H+}$, basic/alkaline has more $\ce{OH-}$. So equal numbers mean neutral.

Answer:

A. Carbon, hydrogen, oxygen, nitrogen

Question 34