Common salt, also known as sodium chloride, is an ionic compound composed of sodium cations (Na+) and chloride anions (Cl-) in a 1:1 ratio. Its chemical formula is represented as NaCl.

Ionic bonds result from the complete transfer of electrons from a metal to a non-metal, creating electrostatic attraction. Covalent bonds result from the mutual sharing of electron pairs between non-metal atoms to achieve stability.

To determine the chemical formula of an ionic compound, the total positive charge must balance the total negative charge. With aluminum having a +3 charge and oxygen having a -2 charge, the criss-cross method indicates that two aluminum ions (+6 total) are required to balance three oxide ions (-6 total), resulting in Al2O3.

Methane consists of a central carbon atom bonded to four hydrogen atoms. Each C-H bond is formed by the sharing of one electron from carbon and one from hydrogen, resulting in four single covalent bonds. The molecule adopts a tetrahedral geometry to minimize electron pair repulsion.

Ionic solids are characterized by a rigid crystal lattice structure, making them hard and brittle. The strong electrostatic attractions result in high melting points. When melted or dissolved in water, the ions become mobile, allowing the substance to conduct electricity effectively.

The formula Al2(SO4)3 consists of two aluminum ions (Al3+) and three sulfate polyatomic ions (SO4^2-). According to IUPAC nomenclature rules for ionic compounds, the cation is named first followed by the anion. Therefore, the name is aluminum sulfate. Sulfite would be SO3^2-, and sulfide would be S^2-, making those options incorrect.

Covalent compounds consist of neutral molecules held together by shared electron pairs. Because they lack the charged ions necessary to interact strongly with the polar water molecules, they are generally insoluble in water, following the 'like dissolves like' principle.

Ionic salts are characterized by strong electrostatic forces between ions, resulting in high melting points and high boiling points. The statement claiming they have low melting points is incorrect, as significant energy is required to break the rigid crystal lattice structure.

A coordinate covalent bond, also known as a dative bond, involves the sharing of a pair of electrons where both electrons originate from one of the two atoms. While protons are central to acid-base chemistry, the coordinate bond is specifically defined by this donor-acceptor electron pair mechanism, distinguishing it from standard covalent or ionic interactions.

Sodium hydroxide (NaOH) is an ionic compound composed of Na+ cations and OH- anions. The bond between the sodium ion and the hydroxide ion is ionic. Within the hydroxide polyatomic ion itself, the oxygen and hydrogen atoms are held together by a polar covalent bond. Therefore, NaOH contains both types of bonding.