Spent fuel that can no longer be used to create energy is waste.
Explanation:
Boiling is defined as a process in which vapor pressure of a liquid substance becomes equal to the atmospheric pressure.
During this change liquid and vapors remain in equilibrium and the equation for this change is as follows.

Therefore, when boiling takes place then average kinetic energy of particles in liquid phase equals to the average kinetic energy of particles in vapor phase.
Hence, we can increase the kinetic energy of particles in liquid phase by increasing the temperature because kinetic energy is directly proportional to temperature as follows.
K.E = 
Answer: Out of the given options bonds connecting atoms in reactants break, and bonds connecting atoms in products form are the changes which takes place when a chemical change occurs.
Explanation:
A change that leads to the change in chemical composition of a substance is called a chemical change.
For example, 
Here, bond between the reactant atoms nitrogen and hydrogen is broken down.
On the other hand, bond connecting the products that is
and
is formed.
Thus,, we can conclude that out of the given options bonds connecting atoms in reactants break, and bonds connecting atoms in products form are the changes which takes place when a chemical change occurs.
Answer: Gravity depends on two main factors.
Explanation: Those factors are mass and distance. I hope this helps!