Question

the complicated molecules that make up living things usually contain carbon. why is carbon so important in these molecules? a. carbon is the lightest and smallest element. b. carbon forms ionic bonds with most elements. c. carbon can only form one bond at a time. d. carbon can form four strong covalent bonds.

Explanation:

• Option A is incorrect: Hydrogen is the lightest and smallest element, not carbon.
• Option B is incorrect: Carbon primarily forms covalent bonds, not ionic bonds, with most elements in biological molecules.
• Option C is incorrect: Carbon has 4 valence electrons, allowing it to form up to 4 bonds, not just one.
• Option D is correct: Carbon's 4 valence electrons let it form four strong covalent bonds with other atoms (like hydrogen, oxygen, nitrogen), enabling the formation of the complex, diverse molecules needed for life.

Answer:

D. Carbon can form four strong covalent bonds.