Which of the following statements is true?
protons have negative charges.
a piece of gold is made only of gold atoms.
all molecules are compounds.
compounds have the same properties as the elements they are made from

Below.

Explanation:

True:

A piece of gold is made only of gold atoms.

Untrue:

Protons have negative charges ( they are positive).

All molecules are compounds . (Oxygen gas O2 is a molecule but not a compound as the 2 atoms are the same).

Compounds have the same properties as the elements they are made from.

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.