Generally speaking mechanical energy is energy which physically moves (the object), while the thermal energy is energy from the movement of atoms.
Basically temperature is a measurement of atomic movement (doesn't move object as a whole).
Hence heat.
Answer:
1 km * 1000 m / km * 100 cm / m = 10^5 cm / km
V = 4 / 3 pi R^3
V = 4 / 3 * pi * (7.01 * 10^5 * 10^5)^3 = 4 / 3 pi * 344 * (10^10)^3
V = 1.443^10^3 * 10^30 = 1.44 10^33cm^3
Yes. It does contain Ions.
Isotope - the same element, but different atomic mass so 1)35 Cl and 37 Cl