If dissolving carbon dioxide in water to form carbonic acid is the forward reaction, what is the reverse reaction that balances this reaction in chemical equilibrium?

Explanation:

When carbon dioxide dissolves and reacts with water, the water and the gaseous     reacts to form a dilute mixture solution of (carbonic acid ).

The reaction is  

This is a forward reaction.  And the symbol    shows that the reaction can be reversible. It means that the reaction can be carried in forward direction as well as in the backward direction.

The reaction attains chemical equilibrium until the reactants and the products no longer changes with time.  

The carbonic acid can also dissociates into carbon dioxide and water in the backward direction.

the atomic mass is the bottom number on the element.

-steel jelly

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.