Which of the following compounds would be found as mostly molecules when placed into water? 
I. Be(OH)₂           II. HNO₃            III. LiOH            IV. (CH­₃)₂NH        V. CaO

• A. I, IV, V
• B. I only
• C. I and IV
• D. IV only
• E. None of the above

Answer: (C)

Verified step by step guidance

1. Understand that when compounds dissolve in water, they can either ionize completely, partially, or remain mostly as intact molecules depending on their nature (ionic or molecular) and their acid/base strength.
2. Identify the nature of each compound: Be(OH)\_2 is a metal hydroxide with some covalent character and is only slightly soluble, so it tends to remain mostly as molecules rather than fully dissociating.
3. HNO\_3 is a strong acid and ionizes completely in water, so it will not be found mostly as molecules but as ions.
4. LiOH is a strong base and ionic compound that dissociates completely into Li\^+ and OH\^- ions in water.
5. (CH\_3)\_2NH (dimethylamine) is a weak base and a molecular compound that does not fully ionize in water, so it remains mostly as molecules.
6. CaO reacts with water to form Ca(OH)\_2, which is ionic and dissociates significantly, so CaO itself would not be found mostly as molecules in water.