Questions

Environmental science is a field that integrates physical, biological and information sciences to the study of the environment, and the solution of environmental problems. This emerged from the fields of natural history and medicine during the Enlightenment.

In brief, it is a scientific study of the natural world and how it is influenced by people.

Megahertz is used to measure wave frequencies, as well as the speed of microprocessors. One MHz represents one million cycles per second. The speed of microprocessors, called the clock speed.

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.