Most organic compounds contain $C$ and which of the following elements?

• A. $H$ydrogen
• B. $\mathrm{Cl}$orine
• C. $S$ulfur
• D. $\mathrm{Mg}$nesium

Answer: (A)

Verified step by step guidance

1. Understand that organic compounds are primarily defined by the presence of carbon (C) atoms bonded to other elements.
2. Recognize that hydrogen (H) is the most common element bonded to carbon in organic molecules, forming hydrocarbons and many functional groups.
3. Consider other elements commonly found in organic compounds, such as oxygen (O), nitrogen (N), sulfur (S), and halogens like chlorine (Cl).
4. Note that magnesium (Mg) is a metal and is not typically a constituent of organic compounds, so it can be excluded.
5. Conclude that the elements most commonly found with carbon in organic compounds include hydrogen (H), chlorine (Cl), and sulfur (S), with hydrogen being the most prevalent.