Question

question 49
in the body, oxygen
a reacts with water to form carbonic acid.
b is used during cellular respiration.
c is a major electrolyte.
d is produced by cells.

question 50
matter is composed of elements, which are composed of ____.
a atoms
b inorganic molecules
c organic molecules
d chemicals

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Explanation:

Question 49

• Option A: Carbon dioxide reacts with water to form carbonic acid, not oxygen. So A is incorrect.
• Option B: During cellular respiration, cells use oxygen to break down glucose and produce energy, carbon dioxide, and water. This is a key process in the body. So B is correct.
• Option C: Major electrolytes include ions like sodium, potassium, chloride, etc. Oxygen is a gas, not an electrolyte. So C is incorrect.
• Option D: Cells produce carbon dioxide, not oxygen. Oxygen is taken in from the environment (like through breathing in humans). So D is incorrect.

• Option A: An element is a pure substance that is composed of only one type of atom. For example, the element carbon is composed of carbon atoms, and the element oxygen is composed of oxygen atoms. So matter (which is made of elements) has elements that are made of atoms. This is correct.
• Option B: Inorganic molecules are made up of atoms (and can be composed of elements), but elements themselves are not composed of inorganic molecules. Inorganic molecules are a level of organization above atoms and elements. So B is incorrect.
• Option C: Organic molecules are also made up of atoms and are composed of elements, but elements are not made of organic molecules. Organic molecules are more complex structures built from elements. So C is incorrect.
• Option D: The term "chemicals" is very broad. Elements are a type of chemical, but saying elements are composed of chemicals is not accurate in the context of the basic structure of matter. Elements are fundamental in terms of their atomic composition. So D is incorrect.

Answer:

B. is used during cellular respiration.

Question 50