answer is A
The kinetic theory is used to explain the behaviour of gases.
One of the assumptions states that "a gas is composed of a large number of identical molecules moving at different speeds".
In the first situation: the mechanism of covection is the main form of heat transfer when warm air from a heater moves around and upward.
In the case of the metal pan the mechanism of heat transfer is conduction.
In the case of sunburn the mechanism is radiation.
In the case of an ice cube melting in a hand, conduction is the most important mechanism.
Answer:
Basically, paramagnetic and diamagnetic refer to the way a chemical species interacts with a magnetic field. More specifically, it refers to whether or not a chemical species has any unpaired electrons or not.
A diamagnetic species has no unpaired electrons, while a paramagnetic species has one or more unpaired electrons.
Now, I won't go into too much detail about crystal field theory in general, since I assume that you're familiar with it.
So, you're dealing with the hexafluorocobaltate(III) ion, [CoF6]3â’, and the hexacyanocobaltate(III) ion, [Co(CN)6]3â’.
You know that [CoF6]3â’ is paramagnetic and that [Co(CN)6]3â’ is diamagnetic, which means that you're going to have to determine why the former ion has unpaired electrons and the latter does not.
Both complex ions contain the cobalt(III) cation, Co3+, which has the following electron configuration
Co3+:1s22s22p63s23p63d6
For an isolated cobalt(III) cation, all these five 3d-orbitals are degenerate. The thing to remember now is that the position of the ligand on the spectrochemical series will determine how these d-orbtals will split.
More specifically, you can say that
a strong field ligand will produce a more significant splitting energy, Δ a weak field ligand will produce a less significant splitting energy, Δ
Now, the spectrochemical series looks like this
http://chemedu.pu.edu.tw/genchem/delement/9.htmhttp://chemedu.pu.edu.tw/genchem/delement/9.htm
Notice that the cyanide ion, CNâ’, is higher on the spectrochemical series than the fluoride ion, Fâ’. This means that the cyanide ion ligands will cause a more significant energy gap between the eg and t2g orbitals when compared with the fluoride ion ligands.
http://wps.prenhall.com/wps/media/objects/3313/3393071/blb2405.htmlhttp://wps.prenhall.com/wps/media...
In the case of the hexafluorocobaltate(III) ion, the splitting energy is smaller than the electron pairing energy, and so it is energetically favorable to promote two electrons from the t2g orbitals to the eg orbitals → a high spin complex will be formed.
This will ensure that the hexafluorocobaltate(III) ion will have unpaired electrons, and thus be paramagnetic.
On the other hand, in the case of the hexacyanocobaltate(III) ion, the splitting energy is higher than the electron pairing energy, and so it is energetically favorable to pair up those four electrons in the t2g orbitals → a low spin complex is formed.
Since it has no unpaired electrons, the hexacyanocobaltate(III) ion will be diamagnetic.
Chemical reactions are at the essence of just about every biological and physical process in the whole universe. Stars form due to chemical reactions, our sun flamed up also because of chemical reactions in its core. Life basically evolved on Earth as an outcome of chemical reactions. The "circle of life" is, at its quintessence, a sequence of chemical reactions. Also our capacity to move and think is an outcome of chemical reactions that happen inside our bodies. Chemical reactions are the reason why new forms of matter are created. Chemical reactions make us comprehend the properties of matter. Chemical reactions make food into fuel for our bodies, they make fireworks blow up, they change food when it is cooked, they make soap remove dirt, and a lot more. Chemical reactions contribute to solving crimes and unravel mysteries. We can even find out which planets and moons are most likely to be able to preserve life. The most significant and momentous discovery made by humans, fire, is just a chemical reaction. Nothing would ever change without chemical reactions
