Which of these statements describes the basic idea of the Valence Shell Electron Pair Repulsion (VSEPR) theory?
1. Molecules repel one another due to intermolecular forces.

2. There is always an octet of electrons around an atom in a molecule

3. Shared and unshared electron pairs repel each other as much as
possible
4. Electrons are attracted to the nucleus of the central atom.

3. Shared and unshared electron pairs repel each other as much as

possible

Explanation:

The variations in the bond angles of molecules and ions can be explained using the valence shell electron pair repulsion theory.

The VESPR model determines the total number of electron pairs (TEP) surrounding the central atom of a specie. The TEP consists of bond pairs BP and lone pairs LP.

All the electron pairs will orient themselves in such a way as to minimize the electrostatic repulsion between them.

The repulsion determines the geometry of the covalent bonds around the central atom. As the number of lone pairs increases from 0 to 2, the bond angles diminishes progressively.

i dont know the answe

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.