Questions

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.

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.

The charophytes are the extant group of green algae that are most closely related to modern land plants.

The blood of some invertebrate animals like the earthworm is red due to haemoglobin pigment, but the pigment is dissolved in the plasma. In vertebrates the same pigment is found in the red corpuscles and not in the plasma.

Radioactive decay is likely to occur when the nuclei of an atom doesn't have enough binding energy to hold the nucleus together due to excess of rotons or nutrons in it.