Answer:
II and IV.
Explanation:
I. (INCORRECT). A model is a tentative to determinate a thing that can't be proved, and it's made based on evidence. If the model can explain the observation in nature, it is considered right, although it can be proved by a theory.
II. (CORRECT). The most accepted model of atoms says that they're formed by tiny particles, protons, neutrons, and electrons, with the first two on the nucleus, and the other surrounding it in an open space.
III. (INCORRECT). A heterogeneous mixture is a mixture of substances that is possible to identify phases of them, such as in oil and water. In the air, isn't possible to identify the constituents, and it's a homogeneous mixture.
IV. (CORRECT). Silver has atomic number 47, which is its number of protons. The atomic mass is the sum of protons and neutrons, so the number of neutrons is 108 - 47 = 61.
The answer would be 833.7
Eu2+ is stable because of the two electrons in its outermost orbit and after losing 4 electrons. Ce +4 is stable
What are lanthanide ions?
All lanthanide elements form trivalent cations, Ln3+, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium. These elements are called lanthanides because the elements in the series are chemically similar to lanthanum.
The Ce metal has the following electronic configuration: [Xe] 4f¹5d¹6s²
It obtains noble gas configuration after losing 4 electrons. Ce +4 is stable, so.
Eu's electronic setup is as follows.
[Xe] 4 f ⁷6s²
[Xe] 4 f ⁷
Eu2+ is stable because of the two electrons in its outermost orbit. Additionally stable is its +3 oxidation state. Ce⁺²
To learn more about lanthanides click on the link below:
brainly.com/question/12756990
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1) Xenon
2) Berylium
3) Aluminium (Assuming 3p = 3rd Period)
4) Tungsten
5) Bromine
6) Xenon again
7) Indium I think
8) Strontium
9) Titanium
10) Oxygen
11) I don't understand that at all XD
12) Rutherfordium
13) Radon
14) Potassium?
15) Argon
So somebody needs to confirm 3, 7, 11, and 14, but I think the rest are correct if you load up a Periodic table
