Sulfur is a non-metal element.

Sulfur is a non-metal element.

• A. a good conductor of electricity. Non-metals, including sulfur, are generally poor conductors of electricity (insulators). Therefore, this statement is not a property of sulfur.
• B. a yellow solid and insoluble in water. Sulfur is typically a yellow solid at room temperature and is known to be insoluble in water. This is a correct property.
• C. found in large underground deposits. Sulfur occurs naturally in large underground deposits, often associated with volcanic activity or salt domes. This is a correct property.
• D. made up of crown-shaped molecule. The most common and stable allotrope of sulfur, rhombic sulfur, consists of $\text{S}_8$ molecules, which have a characteristic crown shape. This is a correct property.

Based on the evaluation, sulfur is not a good conductor of electricity.

The final answer is $\boxed{\text{A}}$.