Compare the mass of the magnesium strip from test tube 1 with the initial mass of the same strip measured in task 1, part A. Is the mass the same, or is it different? If it’s different, explain what may have caused the difference. Compare the mass of the zinc strip from test tube 5 with the mass of the same strip measured in task 1, part A. Based on your observations of the metal strip, explain what factors may have added to its mass or caused a decrease in its mass. Which had the greater effect? Explain your reasoning

What evidence can be used to support the fact that oxidation, reduction, or both took place in test tube 5?

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.

i belive it is water