Explanation:
The reaction equation will be as follows.

Hence, moles of Na = moles of electron used
Therefore, calculate the number of moles of sodium as follows.
No. of moles = 
=
(as 1 kg = 1000 g)
= 195.65 mol
As, Q =
where F = Faraday's constant
= 
=
mol C
Relation between electrical energy and Q is as follows.
E = 
Hence, putting the given values into the above formula and then calculate the value of electricity as follows.
E = 
= 
= 
As 1 J =
kWh
Hence,
kWh
= 3.39 kWh
Thus, we can conclude that 3.39 kilowatt-hours of electricity is required in the given situation.
The balanced chemical reaction is :

Number of moles of Na,
.
Now, from balance chemical reaction we can see that 1 mole of oxygen reacts with 4 moles of sodium.
So, number of moles of oxygen are :

So, amount of oxygen required is :

Therefore, 5.08 gram of oxygen will react with 14.6 gram of sodium.
Answer:
C) The student and desk have to be in contact to apply the force.
Explanation:
I am pretty sure :)
Reactivity - Reactivity refers to how likely or vigorously an atom is to react with other substances. This is usually determined by how easily electrons can be removed (ionization energy) and how badly they want to take other atom's electrons (electronegativity) because it is the transfer/interaction of electrons that is the basis of chemical reactions.
Metals
Period - reactivity decreases as you go from left to right across a period.
Group - reactivity increases as you go down a group
Why? The farther to the left and down the periodic chart you go, the easier it is for electrons to be given or taken away, resulting in higher reactivity.
Non-metals
Period - reactivity increases as you go from the left to the right across a period.
Group - reactivity decreases as you go down the group.
Why? The farther right and up you go on the periodic table, the higher the electronegativity, resulting in a more vigorous exchange of electron
The change of phase from a vapor to a liquid is called condensation.
Hope this helps~