Which type of solid is predicted for HCl, Na, CaCl2???
This is unclear to me what you are asking.
To determine the type of solid for HCl, Na, and CaCl2, we need to consider the nature of the bonding between the atoms present in these compounds.
HCl is a covalent compound consisting of a hydrogen atom bonded to a chlorine atom. Covalent compounds typically exist as either gases, liquids, or low-melting-point solids. Given that hydrogen chloride (HCl) is a gas at room temperature and pressure, it can be inferred that HCl is a gas.
Na is an elemental metal and it is known that metals typically exist as solids at room temperature and pressure. Therefore, sodium (Na) is a solid.
CaCl2 is an ionic compound composed of calcium cations (Ca2+) and chloride anions (Cl-). Ionic compounds usually have high melting and boiling points due to the strong electrostatic attraction between the oppositely charged ions. Therefore, CaCl2 is a solid.
In summary, HCl is a gas, Na is a solid, and CaCl2 is also a solid.