Which of these is accurate?

Question

a

Humans are composed primarily of water.
b

Elements making up the human body are mostly potassium and carbon.
c

By volume, humans are 65% oxygen gas.
d

By mass, humans are 2% calcium.

Answer 1

The most accurate statement among the options provided is:

a. Humans are composed primarily of water.

Humans are made up of approximately 60% to 70% water by weight. The other statements contain inaccuracies regarding the composition of the human body.

Answer 2

why are the others wrong

Answer 3

Here’s a breakdown of why the other statements are incorrect:

b. Elements making up the human body are mostly potassium and carbon.

• While carbon is a major element in the human body (about 18% by mass), potassium is not one of the most abundant elements. The major elements by mass in the human body include oxygen (about 65%), carbon (about 18%), hydrogen (about 10%), nitrogen (about 3%), calcium (about 1.5%), and phosphorus (about 1%), among others. Potassium is important but makes up only about 0.2% of body mass.

c. By volume, humans are 65% oxygen gas.

• This statement inaccurately describes the composition of the human body. While oxygen is a major component in terms of mass, it is primarily found in water (H2O) and organic molecules rather than as free oxygen gas (O2). The human body is about 60-70% water, which contains oxygen, but the portion of the body that is purely oxygen gas (O2) is negligible.

d. By mass, humans are 2% calcium.

• While calcium is an important mineral for the human body (primarily stored in bones), it constitutes about 1.5% of the body mass, not 2%. Other minerals such as phosphorus are also present, but calcium’s mass percentage is often estimated to be around 1-2%, with most references citing it closer to 1.5%.

In summary, the inaccuracies in these options stem from misstatements about the relative abundances of elements and the forms in which they exist in the human body.