Answer:
5.6
Explanation:
Because of the gravity of the earth
The complete answer contains the answer choices.
This is the complete question:
Atoms of which element react spontaneously with Mg2+(aq)? (1)chromium
(2)barium
(3)iron
(4)zinc
Answer: option 2. barium.
Explanation.
1) Mg ²⁺ (aq) is the aquous cation of the metal Mg.
2) Only a metal more reactive than Mg will be able to exchange with it the oxidation states.
3) Mg is an earth alkalyne metal (group 2 of the periodic table). The metals from this group are more reactive than the metals in the groups to its right: 3, 4, 5, 6, 7, ... Only the alkalyne metals (those in group 1) are more reactive than the earth alkalyne metals.
4) Of the list, barium is the only alkalyne metal, so it is more reactive than Mg and will be able to deliver 2 electrons to transform the cations Mg²⁺ into Mg while the very Ba will become Ba²⁺.
5) Chromium, iron and zinc are transition metals, so less metallic (reactive) than Mg.
<u>Answer: </u>The equation which is wrong is 
<u>Explanation:</u>
For the given reaction:

The expression for
is given by:
![K_c=\frac{1}{[O_2]^3}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B1%7D%7B%5BO_2%5D%5E3%7D)
![K_p=\frac{1}{[O_2]^3}](https://tex.z-dn.net/?f=K_p%3D%5Cfrac%7B1%7D%7B%5BO_2%5D%5E3%7D)
The concentration of solids are taken to be 1, only concentration of gases and liquid states are taken. The pressure of only gases are taken.
Relationship between
is given by the expression:

where,
= number of moles of gaseous products - number of moles of gaseous reactants
R = gas constant
T= temperature
For the above reaction,
= number of moles of gaseous products - number of moles of gaseous reactants = 0 - 3 = -3
Hence, the expression for
is:

Therefore, the equation which is wrong is 