How does carbon dioxide malfunction

if in excess the carbon dioxide is harmful to both the humen and other living things.

Explanation:

in our daily life we exhale carbon dioxide after inhaling oxygen.

but if carbon dioxide is in excess  in atmosphere which is caused by burning fossils may cause changes in weather and climate at large due to aerosol particle emittion which inturn cause damage to o-zone layer causing global warming.which are effect to aquatic life and also to human.

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.