Question

which statement describes the properties of lanthanoids and actinoids? (1 point)
○ they are malleable and lustrous, and they tend to be poor conductors of both electricity and thermal energy.
○ they are brittle and dull, and they tend to be poor conductors of both electricity and thermal energy.
○ they are malleable and lustrous, and they tend to conduct both electricity and thermal energy.
○ they are brittle and dull, and they tend to conduct both electricity and thermal energy.

Explanation:

Lanthanoids and actinoids are part of the inner transition metals. Metals in general are malleable (can be hammered into sheets), lustrous (shiny), and good conductors of electricity and thermal energy. Option 1 says they are poor conductors, which is wrong. Option 2 says they are brittle (a property of non - metals/metalloids) and poor conductors, wrong. Option 4 says they are brittle (wrong for metals) and dull (non - lustrous, wrong for metals). Option 3 correctly states their metallic properties: malleable, lustrous, and good conductors of electricity and thermal energy.

Answer:

C. They are malleable and lustrous, and they tend to conduct both electricity and thermal energy (assuming the third option is labeled C, if the original options were labeled as A, B, C, D with the third option being C; adjust the label according to the actual option numbering in the original question, but the content should be as above).