It'd be a physical change. This is because it's a change in the state of matter and not altering the chemical structure of water
Net overall dissociation:
Na2CO3 ---> 2Na(-) + CO3(2-)
*The ion charge is in parenthesis
Answer: The equation for kinetic energy is 
Explanation:
Kinetic energy is the energy possessed by the virtue of object's motion. It is defined as the work needed to move a body of a given mass from rest to its velocity.
Mathematically,

where,
m = mass of the body
v = velocity of the body.
Hence, above equation relates kinetic energy to the mass and velocity of the body.
Answer:
Either B or C. Composition or the Distance from the Earth.