Which is the best example of the law of conservation of energy? O A basketball stops bouncing because its energy disappears.
O A rolling skateboard slows down because some of its kinetic energy changes to heat.
O A falling book hits the ground and all of its energy is destroyed.
O A toy car gains speed as it moves down a ramp because the ramp creates energy.

B

Explanation:

A rolling skateboard slows down because some of it's kinetic energy changes to heat

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.