Answer:
atomic number of Be =4
electronic configuration :1s²2s²
but for Be2+ atomic number = 4-2 =2
electronic configuration : 1s²
Changes in matter occur every day. There are two types of ways matter can be altered; physically and chemically. Physical changes do not change the composition of the matter while chemical changes occur when one or more substances turn into a completely new substance. Physical changes can be seen through an altering of the substances physical property. A substances physical property is observed and measured without changing the composition of the subject. Descriptive words that would help to identify a substance’s physical property include hard, soft, brittle, flexible, heavy, and light just to name a few. Let’s say you’re eating, throughout the day your stomach starts to growl that is what happens when your stomach is digesting your food. Digestion is an example of chemical change. Chemical change happens every day and more than half the time we don’t realize it whether it’s metal starting to rust, or our food starting to rot. Physical change can happen when your popsicle starts to melt, or your water starting starting to boil. These are examples of physical change.
Salutations!
<span>In a laboratory experiment, John uses a mesh to separate soil particles from water. Which technique of separation is he using?
The technique that John is using is the filtration technique. Filtration is a technique to separate the solid which is insoluble from the liquid. For instance: Sand and water, sand is insoluble, thus it stays in the filter paper, while the water proceeds through the filter paper.
Hope I helped :D</span>
Answer:
No.of moles of C is , n = mass/molar mass = 75.46 g / 12 (g/mol) = 6.3 moles No.of moles of H is , n' = mass/molar mass = 4.43 g / 1.0(g/mol) = 4.43 moles No.of moles of O is , n'' = mass/molar mass = 20.10 g / 16(g/mol) =1.25 moles Ratio to the no.of moles of C,H& O is 6.3 : 4.43 : 1.25 In the simple integer ratio is ( 6.3/1.25) : ( 4.43/1.25) : (1.25/1.25) 5.04 :3.5 : 1
Explanation:
Delta E = Ef - Ei
E = energy , h = plank constant , v = frequency
h= 6.626 * 10 ^-34 j*s , T = 10 ^ 12 , v = 74 * 10 ^12 Hz , Hz = s^-1
E = ( 6.626 * 10^ -34 j*s) ( 74 * 10 ^ 12 s^ -1 ) = 4.90 * 10 ^ -20 J
Delta E = Ef - Ei
-4.90 * 10 ^ -20 J = -2.18 * 10 ^ -18J ( 1/4 ^2 - 1/x ^2)
0.0225 = 0.0625 - ( 1/x ^ 2)
0.225 - 0.0625 = - 1/ x ^ 2
- 0.0400 = - 1/x ^2 = -1 / - 0.0400 = x^2
25 = x^2
x = 5
