Question

A crystal of $LiF$ (lithium fluoride) is BEST described by which of the following statements?

• A. Soft, has a low melting point, and is a good electrical conductor.
• B. Soft, has a low melting point, and is a poor electrical conductor.
• C. Hard, has a high melting point, and is a good electrical conductor.
• D. Hard, has a high melting point, and is a poor electrical conductor.

Answer 1

Answer: (D)

Hard, has a high melting point, and is a poor electrical conductor.

$LiF$ is hard.

According to Fajon's rule, lithium polarises flurorine to a great extend hence it is mostly covalent and less ionic. Therefore poor conductor of electricity and high melting point.