Which of the following statements is true? water is easily polluted because it can dissolve harmful chemicals o when water freezes, it contracts and becomes more dense. thermal pollution happens when cold water is released into an ecosystem adhesion describes a water molecule's attraction to another water molecule.

The statement "Water is easily polluted because it can dissolve harmful chemicals" is true. Water is really good at dissolving stuff. When harmful chemicals are dissolved in water, water becomes polluted.

1 is the answer to this problem

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.