Answer with Explanation:
A "chemical change" occurs when the structure of the molecules change. If there's no change in structure, it is called a "physical change." This also means that a <em>chemical reaction </em>has to occur for something to be considered a chemical change.
Gasoline when used as a fuel is being transformed into other forms of energy. It undergoes a process called <em>"combustion."</em>
When used as a fuel for cars, <em>the gasoline is being burned to produce </em><u><em>heat energy.</em></u> This energy is then converted into <u><em>mechanical energy</em></u> that allows the car to move. Clearly, the gasoline has undergone a chemical change.
Answer:

Explanation:
According to the boiling point elevation law described by the equation
, the increase in boiling point is directly proportional to the van 't Hoff factor.
The van 't Hoff factor for nonelectrolytes is 1, while for ionic substances, it is equal to the number of moles of ions produced when 1 mole of salt dissolves.
would produce 2 moles of ions per 1 mole of dissolved substance, sodium and bromide ions.
is insoluble in water, so it would barely dissociate and wouldn't practically change the boiling point.
would dissociate into 3 moles of ions per 1 mole of substance, two potassium cations and one sulfide anion.
is a gas, it would form some amount of carbonic acid when dissolved, however, carbonic acid is molecular and would yield i value of i = 1.
Therefore, potassium sulfide would raise a liquid's boiling point the most if all concentrations are equal.
Answer:
Noble Gases
Explanation:
The Noble Gases have a full valence shell of 8 electrons. They are stable in that sense.