Network solids are hard and have high melting points. which statement explains these properties?
a.
the atoms are held together with large networks of metallic bonds.
b.
the atoms are held together with large networks of electromagnetic forces.
c.
the atoms are held together with large networks of intermolecular forces.
d.
the atoms are held together with large networks of covalent bonds.

The correct answer is A the atoms are held together with large network of metallic bonds.

Explanation:

Metallic bond is a specific type of bond that is formed by interaction of many detached negatively charged electron with positively charged ions or cations,which provides a definite structure to the substance.

Due to the low ionization energy the electrons present in the outerorbital can be de localized throughout the metal.The de localized electrons able to freely move around the crystalline structure.

 There is a presence of strong interaction between negatively charged electrons and positively charged ions which is responsible for high melting and boiling point of metals.

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.

the correct answer to this question is 2