the speed of sound in seawater is 1470 m/s. a dolphin sends out a click that reflects off of an
object 150.0 m away. how long does it take from the initial click for the echo to return to the
dolphin?

0.204 s

Explanation:

The speed of sound is defined as the distance traveled in a especific time :  

Where:  

is the speed of sound  in seawater

is the time the sound wave travels from the dolphin and then returns after the reflection

is twice the distance between the dolphin and the object to which the sound waves are reflected

Finding :

Finally:

freezing

deposition

condensation

explanation;

melting also called fusion is the process where solid becomes liquid, sublimation is the process where solid becomes gaseous without first changing to liquid, deposition involves change from gaseous to solid state, freezing involves change from liquid to solid, boiling or evaporation involves change of liquid to gaseous state, while condensation is the change from gaseous state to liquid state.

endothermic reactions involves absorption of heat from the surroundings or the environment while exothermic reactions involves loss of heat energy to the surroundings.

in this case, sublimation, evaporation and melting are endothermic reactions (gain energy from the environment) while, freezing, deposition and condensation are exothermic (loss of energy to the surroundings) reactions.

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask