Answer:
A scientist is studying a shock wave from an earthquake, he is studying mechanical wave.
Explanation:
The shock waves are experienced during earthquake. At the area of increased pressure shock wave are created as the object in that places moves faster as compared to the speed of sound. Shock wave are type of mechanical wave. For its transfer it requires a medium. An electromagnetic wave can travel of its own without any medium, under electromagnetic wave gamma ray and radio wave comes. they are transverse wave.
Answer: The given statement is false.
Explanation:
Precipitation reaction is defined as the chemical reaction in which two aqueous solution upon mixing together results in the formation of an insoluble solid.
For example, 
Here AgCl is present in solid state so, it is the precipitate.
But it is not necessarily true that two aqueous solutions will always result in the formation of a precipitate.
For example, 
Hence, we can conclude that the statement precipitation reactions always occur when two aqueous solutions are mixed, is false.
A) Temperature does not affect reaction rate