a) These telescopes must make observations above much of the water vapor in the atmosphere because water can block infrared rays.
Explanation:
Ground- based infrared telescopes are placed in a high altitudes dry climates because the telescopes must make observations above much of water vapor since they cut and block them off.
- Telescopes are devices that are used to observe very distant objects.
- An infrared telescope is sensitive to infrared rays.
- Infrared rays are part of the electromagnetic radiations.
- These rays are usually blocked off by the presence of water vapor.
- Desert areas that lacks water vapor in the atmosphere are the most desired for sighting such facilities.
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Answer: This option is incorrect: <span>B. Covalent compounds are held together by much stronger interparticle forces than are ionic compounds.
Justification:
Ionic bonds, held by ionic compounds, are much stronger than covalent bonds, held by covalent compounds.
In ionic bonds one element yields one or more electrons forming a cation (a positively charged ion) and the other element accepts the electrons forming an anion (a negatively charged ion).
The anion and the cation are electrostatically atracted by each other. This electrostatic atraction force, named ionic bond, is very strong.
As result of this, the ionic compounds form strong crystals with high boiling and fusion points. A good example of this the sodium chloride, formed by the union of cation Na(+) and anion Cl(-).
The covalent bonds are result of sharing electrons and do not form ions. This bond is weaker than the ionic bond.
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True
as a compound tends to be formed from the reaction between two or more elements to produce stable compounds if they had a charge they would be classified as an ion
hope that helps
Answer:
In the n = 3 energy level
Explanation:
There's is no further explanation for this.
All the electrons in an energy level are distribuited according to the period in the periodic table they are.
So, if we have an atom in period 1, like Hydrogen (H), that atom would only have 1 level energy (n = 1) and in that level, we only have the sub level 1s.
Electrons in the 3d sublevel, are found mostly in all the transition metals of period 3, and it can go from 1 to 10 electrons. To be with the 3d sub level it's neccesary that the energy level to be 3.
energy levels beyond that, like n = 4, we have electrons occupying the 3d sub level, so, primordly, the 3d is found only in energy level 3.
Hope this helps
