Question

1. which of the following is true about compounds?

they can be physically separated into their component elements.
they are substances.
they have properties similar to those of their component elements.
they have compositions that vary.

Explanation:

• Compounds are substances formed by chemical combination of elements. They cannot be physically separated into elements (requires chemical methods). Their properties are different from component elements (e.g., water \(H_2O\) vs hydrogen and oxygen). Their composition is fixed (e.g., \(H_2O\) always has 2 H and 1 O).
• Since compounds are substances (fixed composition, definite properties), this option is correct.

Answer:

They are substances.