The atoms that would be expected to be diamagnetic in the ground state is magnesium
The magnetism of an atom refers to its electronic configuration. A diamagnetic atom is an atom whose electrons are all paired.
A paired electron is an electron that occurs in pairs in its orbital shell.
At their respective ground state, the electronic configuration of the given elements are as follows:
The electronic configuration of magnesium is 1s²2s²2p⁶3s². As such its a diamagnetic atom.
The electronic configuration of Potassium is 1s²2s²2p⁶3s²3p⁶4s¹. Hence, Potassium has one unpaired electron in its outermost shell.
The electronic configuration of Chlorine is 1s²2s²2p⁶3s²3p⁵. Hence, Chlorine has one unpaired electron in its outermost shell.
The electronic configuration of Cobalt is 1s²2s²2p⁶3s²3p⁶3d⁷4s². Hence, the unpaired electrons of Cobalt in its outermost shell are three.
Therefore, the atoms that are diamagnetic in the ground state is magnesium.
Learn more about diamagnetic atoms here:
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First one is true second one is False
Answer:
Ka = 
Explanation:
Initial concentration of weak acid =
pH = 6.87
![pH = -log[H^+]](https://tex.z-dn.net/?f=pH%20%3D%20-log%5BH%5E%2B%5D)
![[H^+]=10^{-pH}](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D10%5E%7B-pH%7D)
![[H^+]=10^{-6.87}=1.35 \times 10^{-7}\ M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D10%5E%7B-6.87%7D%3D1.35%20%5Ctimes%2010%5E%7B-7%7D%5C%20M)
HA dissociated as:

(0.00045 - x) x x
[HA] at equilibrium = (0.00045 - x) M
x = 
![Ka = \frac{[H^+][A^{-}]}{[HA]}](https://tex.z-dn.net/?f=Ka%20%3D%20%5Cfrac%7B%5BH%5E%2B%5D%5BA%5E%7B-%7D%5D%7D%7B%5BHA%5D%7D)

0.000000135 <<< 0.00045

Explanation:
the answer will be 98.4 kJ
Potassium carbonate<span> (K</span>2CO3<span>) is a white salt, </span>soluble in water<span> (</span>insoluble<span> in ethanol) which forms a strongly alkaline solution. </span>