Answer:
6 different frequencies
Explanation:
From energy level 1 to 2 is one frequency, from energy level 1 to 3 is one frequency and From energy level 1 to 4 is one frequency. So, we have a total of 3 frequencies for transition from energy level 1.
From energy level 2 to 3 is one frequency and from energy level 2 to 4 is one frequency. So, we have a total of 2 frequencies for transition from energy level 2.
From energy level 3 to 4 is one frequency.
So we have a total of 3 + 2 + 1 different frequencies = 6 different frequencies.
Note that the reverse process for each step produces the same frequency as the step in consideration.
Answer:
Explanation:
All three lighter boron trihalides, BX3 (X = F, Cl, Br), form stable adducts with common Lewis bases. Their relative Lewis acidities can be evaluated in terms of the relative exothermicities of the adduct-forming reaction. Such measurements have revealed the following sequence for the Lewis acidity: BF3 < BCl3 < BBr3 (in other words, BBr3 is the strongest Lewis acid).
This trend is commonly attributed to the degree of π-bonding in the planar boron trihalide that would be lost upon pyramidalization (the conversion of the trigonal planar geometry to a tetrahedral one) of the BX3 molecule, which follows this trend: BF3 > BCl3 > BBr3 (that is, BBr3 is the most easily pyramidalized). The criteria for evaluating the relative strength of π-bonding are not clear, however. One suggestion is that the F atom is small compared to the larger Cl and Br atoms, and the lone pair electron in the 2pzorbital of F is readily and easily donated, and overlaps with the empty 2pz orbital of boron. As a result, the [latex]\pi[/latex] donation of F is greater than that of Cl or Br. In an alternative explanation, the low Lewis acidity for BF3 is attributed to the relative weakness of the bond in the adducts F3B-L.
I believe the correct answer from the choices listed above is option A. Fan blades would be an analogy for electron cloud model. Austrian physicist Erwin Schrödinger (1887-1961) developed an “Electron Cloud Model<span>” in 1926. It consisted of a dense nucleus surrounded by a cloud of electrons. Hope this helps.</span>
Answer:
The correct answer is - c. adding 10 mL bleach to 90 mL water.
Explanation:
To prepare a effective disinfecting solution to clean the countertops is a bleasce solution of 10% solution of bleach. The ten percent of the bleach solution means there are one volve of bleach and 9 volume of clean water in this solution.
So, preparing the 1/10 or ten percent solution is where adding 10 ml of bleach which is diluted to 90 ml clean water. This diluted solution can be use as disinfecting solution.
