4. a crystalline solid is brittle, has a high melting point, and has low electrical conductivity. which of the following describes the type of bonds within it?

a. ionic bonds between metals and nonmetals

b. covalent bonds between molecules

c. metallic bonds between atoms

d. covalent bonds between ions

5. on the basis of structure, which of the following solids is the most brittle?

a. caf2

b. c6h12o6

c. cu

d. au