Describe how calcium and fluorine bond together to form calcium fluoride. The electron arrangement of each atom is shown.

Detail is given below.

Explanation:

Calcium is alkaline earth metal. It has two valance electron. Thus calcium needs six more electron to complete the octet. Thus, its very easy for calcium to remove its two electron and get complete octet.

Electronic configuration of Ca:

Ca₂₀ = [Ar] 4s²

While,

Fluorine is halogen. It has seven valance electrons. It needed only one electron to complete the octet. When it combine with calcium , calcium loses two electrons thus two atom of fluorine combine with one atom of fluorine and stable compound calcium fluoride is formed.

Electronic configuration of F:

F₉  = [He] 2s² 2p⁵

Chemical equation:

Ca  + F₂     →     CaF₂

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.