Question

Which statement about covalent compounds is true

Answer 1

I would say it's D. Usually covalent compounds are very brittle so that means that the bond between atoms are weak

Answer 2

Answer is: B. they are poor conductors of heat.

Ionic compounds are good good electricity and heat conductors, because ionic compounds (for example sodium chloride NaCl) have mobile ions (cations and anions) that are able to transfer electrical charge. This compounds also conduct heat, because the ions are next to each other, so energy can be transferred efficiently from one place to another.

On the other hand, covalent compound (for example methane) are usually bad electricity and heat conductors,  because molecules aren far from each other, so heat transfer is less efficient. They do not form ions and atoms are less positive and negative than in ionic compounds.