Which of the following compounds contains only nonpolar covalent bonds?

• A. HCl
• B. O_2
• C. H_2O
• D. NO_3

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the difference between polar and nonpolar covalent bonds. A nonpolar covalent bond occurs when two atoms share electrons equally, which usually happens between atoms of the same element or atoms with very similar electronegativities.
2. Step 2: Analyze each compound's bonds by considering the atoms involved and their electronegativities. For example, in HCl, hydrogen and chlorine have different electronegativities, so the bond is polar covalent.
3. Step 3: Look at O_2, which consists of two oxygen atoms bonded together. Since both atoms are identical, they share electrons equally, making the bond nonpolar covalent.
4. Step 4: For H_2O, oxygen and hydrogen have different electronegativities, so the O-H bonds are polar covalent, not nonpolar.
5. Step 5: For NO_3 (nitrate ion), nitrogen and oxygen have different electronegativities, and the bonds are polar covalent. Therefore, only O_2 contains purely nonpolar covalent bonds.