Which of the following types of compounds are also known as alkalis and consist of hydrogen, a metal, and oxygen?

• A. Salts
• B. Acids
• C. Bases
• D. Oxides

Answer: (C)

Verified step by step guidance

1. Understand the definition of alkalis: Alkalis are a subset of bases that dissolve in water to produce hydroxide ions (OH⁻).
2. Recognize that alkalis typically consist of a metal combined with hydroxide ions, which means they contain hydrogen, a metal, and oxygen in the form of OH⁻ groups.
3. Review the options: Salts are ionic compounds formed from acids and bases, acids release H⁺ ions in solution, oxides are compounds of oxygen with another element but do not necessarily contain hydrogen.
4. Identify that bases, specifically alkalis, fit the description because they contain metal cations and hydroxide ions (OH⁻), which include hydrogen and oxygen.
5. Conclude that the compounds known as alkalis, containing hydrogen, a metal, and oxygen, are bases.