Answer: Diborane, B 2 H 6.
- A Methane, CH<sub>4</sub>
- B Diborane, B<sub>2</sub>H<sub>6</sub>
- C Water, H<sub>2</sub>O
- D Ammonia, NH<sub>3</sub>
Correct answer: B. Diborane, B<sub>2</sub>H<sub>6</sub>
Explanation: Diborane B<sub>2</sub>H<sub>6</sub> has fewer electrons than needed for normal covalent bonds, making it an electron-deficient hydride of the Group 13 element boron.
Each water molecule's O-H bonds (covalent, solid) can hydrogen-bond (dashed) to neighbouring molecules, forming an extended network responsible for water's unusually high boiling point and density anomaly.
Concept context
The simplest and most abundant element in the universe. Study its unique position in the periodic table, isotopes (protium, deuterium, tritium), properties of water and hydrogen peroxide, and industrial uses.