Answer:
For temperatures higher than 533.49 K we will see a spontaneous reaction, and for temperatures lower than that the reaction will not be spontaneous.
Explanation:
When are chemical reactions spontaneous? To find out we need to look at the reaction's change in Gibbs Free energy:
When this is greater than zero, the reaction isn't spontaneous, when it is less than zero, we have a spontaneous reaction. The reaction must then change from spontaneous to non spontaneous when 
. If we insert that into our equation we get:
That is the temperature at which the reaction's spontaneity will change, plugging in our values we find:
At that temperature we have .
Now, at a temperature greater than this one, the entropy term in our equation for the Gibbs' free energy of reaction will take over, and make 
, thus the reaction will be spontaneous.
On the other hand, if we lower the temperature, we will have a smaller entropy term, and we will have: 
. That is, the reaction will not be spontaneous. Therefore for temperatures higher than 533.49 K we will see a spontaneous reaction, and for temperatures lower than that the reaction will not be spontaneous.
When we have the balanced equation for this reaction:
AB3 ↔ A+3 + 3B-
So we can get Ksp:
when Ksp = [A+3][B-]^3
when [A+3] = 0.047 mol and from the balanced equation when
1 mol [A+3] → 3 mol [B-]
0.047 [A+3] → ??
[B-] = 3*0.047 = 0.141
so by substitution in Ksp formula:
∴Ksp = 0.047 * 0.141^3
= 1.32x10^-4
Answer : The correct option is, Only Student B
Explanation :
Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.
In the Lewis-dot structure the valance electrons are shown by 'dot'.
The given molecule is, 
As we know that nitrogen has '5' valence electrons and hydrogen has '1' valence electron.
Therefore, the total number of valence electrons in = 5 + 3(1) = 8
According to Lewis-dot structure, there are 6 number of bonding electrons and 2 number of non-bonding electrons.
The Lewis dot structure of student A is wrong because there is a coordinate bond present between the nitrogen and hydrogen is not covalent.
Thus, the correct Lewis-dot structure of is shown by the student B.
The force on the wall is actually the pressure exerted by gas molecules
Higher the pressure more the force exerted on the walls of container
The pressure depends upon the number of molecules of a gas
In a mixture of gas the pressure depends upon the mole fraction of the gas
As given the mole fraction of He is more than that of H2 therefore He will exert more pressure on the wall
The ratio of impact will be
H2 / He = 2/3 / 1/3 = 2: 1
After some thinking I have come to the conclusion that the answer is C.
