Hydrogen can form ______ covalent bond(s) and oxygen can form ______.

• A. two; two
• B. one; two
• C. two; one
• D. one; one

Answer: (B)

Verified step by step guidance

1. Recall the valence electron configuration of hydrogen and oxygen atoms. Hydrogen has 1 valence electron, and oxygen has 6 valence electrons.
2. Understand that hydrogen needs 1 more electron to complete its outer shell (which holds 2 electrons), so it can form only one covalent bond.
3. Recognize that oxygen needs 2 more electrons to complete its octet (8 electrons in its outer shell), so it can form two covalent bonds.
4. Use this information to fill in the blanks: hydrogen forms one covalent bond, and oxygen forms two covalent bonds.
5. Therefore, the correct answer is: 'one; two'.