Questions

The USSR( now a Common Wealth of Independent States) is spread over Europe and Asia

Processes that require or give off heat will be limited to changes of state, known as phase changes, and changes in chemical constitution, or chemical reactions. Changes of state involve a solid melting, a liquid freezing, a liquid boiling or a gas condensing.

An exothermic process is one that gives off heat, which is transferred to the surroundings. An endothermic process is a reaction which heat has to be supplied to the system from the surroundings.

Here in all the given options, heat is taken away from them to change there phase. 

Liquid to Solid --- Freezing

Gas to Liquid --- Condensation

Gas to Solid --- Deposition 

are all examples of exothermic processes.

In thermodynamics, deposition is a phase transition in which gases are directly transformed to solids without converting to liquids first.

For example, watervapour is directly changed to ice without first becoming to liquid water. In this process, heat is released making the process exothermic process.

Saliva is produced by the salivary gland which helps in food digestion.

Option A) contains fluoride to harden the tooth enamel is not the function of saliva.

This is only possible when that doctor is boy's mother.