IF ₅ The ground state and the excited state outer electronic configuration of iodine(Z = 53) are represented below

In IF ₅  ,I is sp³  d² hybridised therefore,shape of IF ₅  is square pyramidal as it contains one lone pair of electrons
    

\({ NO }_{ 2 }^{ + }\)and CO₂ are sp hybridized, therefore, they have linear shape. 

 \({ { NO }_{ 2 }^{ - } }\) and O₃ are sp² hybridised.Both have lone pair of electrons but in former case it is not donated. Thus, their shape is angular.
   

The central atom Br has seven electrons in the valence shell. Five of these will form bonds with five fluorine atoms and the remaining two electrons are present as one lone pair. Hence, total pairs of electrons are six (5 bond pairs and 1 lone pair).
To minimize repulsion between lone pairs and bond pairs, the shape becomes square pyramidal.

XeF₄ = 4bp + 2lp (This is because Xe contains 8 valunce electrons) = square planar geometry.

In NF₃, N is surrounded by three F atoms and a lone pair thus, have lp-bp repulsion along with bp-bp repulsion.
Thus, its shape is pyramidal.
In BF₃, B is surrounded by only three F atoms, i.e. have no lone pairs, so only repulsion present in it is bp - bp.
Thus, its shape is triangular planar.

There is greater intermolecular hydrogen bonding in H₂ O than that in HF as each H₂ O molecule forms four H-bonds with water molecules,, whereas HF forms only H-bonds with other HF molecules. Greater the intermolecular H-bonding, greater is the viscosity. Hence, HF is less viscous than  H₂ O

This is because of intermixing of 2s and 2p_z orbitals because of their close proximity. Due to intermixing, \({ \sigma 2p }_{ z }\) molecular orbital becomes higher in energy than  \({ \pi 2p }_{ x }\) and  \({ { \pi 2p } }_{ y }\)  molecular orbitals.

This is due to greater repulsion on the axial bond pairs by the equatorial bond pairs of electrons.

A covalent bond is formed by the overlap of half-filled atomic orbitals.

Atomic orbitals  with comparable energies and proper orientation overlap to form molecular orbitals

AIF₃ is an ionic compound whereas SiF₄ is a non-polar covalent compound. Hence, interparticle forces in AIF₃  are much stronger that's why it is a high melting solid.

All the hybrid orbitals have same shape. However, their sizes are in the order : sp < sp² < sp³

Electronegativity of an element is the tendency of its atom to attract the shared pair of electrons towards itself in a covalent bond. Electron gain enthalpy of an element may be defined as the as the energy released when a neutral isolated gaseous atom accepts an extra electron to form the gaseous negative ion, i.e anion.
\(\underset { Neutral \ gaseous \ atom }{ X(g) } +{ e }^{ - }\longrightarrow \underset { Anion }{ { X }^{ - }(g) } ;\Delta H={ \Delta }_{ eg }H\)
Greater the amount of energy released in the above process, higher is the electron gain enthalpy of the element. Electronegativity differs from electron gain enthalpy because electronegativity is a property of an atom in the bonded state while electron gain enthalpy relates to atoms in their isolated gaseous states.

CuSO₄.5H₂O has ionic, covalent, coordinate and hydrogen bonds.