3. Spheres are packed more efficiently in Box B, because the spheres of different layers fit into the spaces in the layer below. Either count the spaces in layer 1, or use spheres provided by your teacher, to determine the number of spheres that could be placed in layer 2.

A common prank on college campuses is to switch the salt and sugar on dining hall tables, which is usually easy because the substances look so much alike. Yet, despite the similarity in their appearance, these two substances differ greatly in their properties, since one is a molecular solid and the other is an ionic solid. How do the properties differ and why?

Why do liquids have a vapor pressure? Do all liquids have vapor pressures? Explain. Do solids exhibit vapor pressure? Explain. How does vapor pressure change with changing temperature? Explain.

The shape of the meniscus of water in a glass tube is different from that of mercury in a glass tube. Why?

The structures of some common crystalline substances are shown below. Show that the net composition of each unit cell corresponds to the correct formula of each substance.

6. Determine if the following compounds are metallic solids, ionic solids, network atomic solids, or molecular solids based on their properties. These are all actual chemical compounds. a. This material is hard and melts at a temperature of 16100 C. It dissolves only with difficulty in very reactive acids and doesn't conduct electricity when molten. It forms colorless crystals. (quartz) b. This material forms colorless crystals that have a melting point of 770° C. It is hard, brittle, and dissolves well in water. (potassium chloride)

a)A Boy received a task on indicating which one is diamond or cubic zirconia. They both look exactly the same. What should he do to differentiate these two crystals? Elaborate. b) FIGURE 2 shows a diamond structure. Determine the volume density of the atom if the given lattice constant is 5.45 A. (Given A -1x10^-¹⁰ m).