Calcium has a valency of +2, and the phosphate ion (PO4) has a charge of -3. To achieve electrical neutrality, three calcium ions (3 x +2 = +6) must balance two phosphate ions (2 x -3 = -6), resulting in the formula Ca3(PO4)2.

Ionic bond formation is a multi-step process. Low ionization energy of the metal is required to form the cation, high electron affinity of the non-metal is needed to form the anion, and high lattice energy is necessary to stabilize the resulting crystal structure. Therefore, all these energetic factors are critical for the formation and stability of an ionic bond.

Valency is defined by the number of chemical bonds an atom forms. In ammonia (NH3), the nitrogen atom is bonded to three hydrogen atoms, each via a single covalent bond, thus its valency is 3.

In the formula Na2X, sodium (Na) has a +1 charge. Since there are two sodium atoms, the anion X must have a -2 charge to balance the total charge. Aluminium (Al) typically forms a +3 ion (Al3+). To form a neutral compound with an X2- anion, the charges must be balanced: 2 atoms of Al (+6 total) and 3 atoms of X (-6 total), resulting in Al2X3.

In standard covalent bonding, the maximum number of bonds between two atoms is three, forming a triple bond (one sigma bond and two pi bonds). While quadruple bonds exist in certain transition metal complexes due to d-orbital overlap, in the context of general chemistry and main group elements, the triple bond is the recognized maximum for stable molecular structures.

In ammonia (NH3), the nitrogen atom forms three covalent bonds with three hydrogen atoms to achieve a stable octet configuration. Valency is defined as the combining capacity of an element, which in this case corresponds to the three electrons shared by nitrogen.

Covalent bonding occurs when atoms share valence electrons to attain a stable electronic configuration, typically an octet, in their outermost shell. This sharing allows atoms to achieve the stability of a noble gas configuration, which is the primary driving force for the formation of covalent molecules.

A covalent bond is defined by the sharing of electron pairs between atoms. A single bond involves the sharing of one pair (two electrons). Consequently, a double covalent bond involves the sharing of two pairs of electrons, totaling four electrons shared between the two bonded atoms to achieve stability.

Electrovalent or ionic compounds consist of ions held together by strong electrostatic forces. In the solid state, these ions are fixed in a lattice and cannot conduct electricity. However, when melted (fused) or dissolved in water, the ions become mobile, allowing the substance to conduct an electric current.

Ionic compounds are generally insoluble in non-polar solvents like alcohol due to their high lattice energy. In the solid state, ions are locked in a rigid crystal lattice and cannot move, making them poor conductors of electricity. They only conduct when molten or dissolved in water, where ions become mobile. Thus, statement 1 is correct, and statement 2 is incorrect.