I was hoping that some choices would be given to choose from. As there are no choices given, so i am answering the question based on my knowledge and hope that it comes to your help. Calcium hydroxide is a good example of Arrhenius base. An Arrhenius base is actually a substance that releases a hydroxyl ion in water.
It is a bit like a video game because when you dumb it down, it's basically a small robotic thing that is controlled by a controller. In video games, you have an avatar being controlled inside a game using a gamepad, in surgery you have a little machine inside of a person's body being controlled using a computer.
Answer:
168°C is the melting point of your impure sample.
Explanation:
Melting point of pure camphor= T =179°C
Melting point of sample =
= ?
Depression in freezing point = 
Depression in freezing point is also given by formula:

= The freezing point depression constant
m = molality of the sample = 0.275 mol/kg
i = van't Hoff factor
We have:
= 40°C kg/mol
i = 1 ( non electrolyte)




168°C is the melting point of your impure sample.
Answer:
Energy is added (postive enthalpy)
Explanation:
Ice melting means solid turns into liquid. Solid is more stable than liquid thus you must put in energy to weaken the forces of solid and turn it into liquid. Thus, you must put in energy to melt ice. This makes the enthalpy of the system to be positive.
Answer:
Oxygen is in excess.
Explanation:
The coefficients of the balanced equation create a mole ratio that shows the ratio of how many reactants are used up and products are created.
The mole ratio of Mg to O2 in this equation is 2:1, which means that for every two moles of Mg used, there will be 1 mole of O2 used.
If we have 3.00 moles of Mg, we will only need 1.5 moles of oxygen to completely burn the Mg. Therefore, when all 3.00 moles of Mg are used, there will still be some of the 2.20 moles of oxygen remaining.