Why sodium chloride is a poor conductor of electricity in solid state?​

Because the electrons in this ionic compound arent free to move and so cannot carry charge. For an iconic compound to conduct electricity it must be a liquid, either in a molten form or dissolved in water.

Explanation:

Is this clear?

Solid NaCl is a bad conductor of electricity because the charged particles (ions) in solid NaCl are not capable of moving as they are bound by strong electrostatic forces. As a result, they can not conduct electricity. However, water ions are capable of moving when NaCl is dissolved in it and hence conduct electricity.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.