T is amount after time t
<span>Ao is initial amount </span>
<span>t is time </span>
<span>HL is half life </span>
<span>log (At) = log [ Ao x (1/2)^(t/HL) ] </span>
<span>log (At) = log Ao + log (1/2)^(t/HL) </span>
<span>log (At) = log Ao + (t/HL) x log (1/2) </span>
<span>( log At - log Ao) / log (1/2) = t / HL </span>
<span>log (At/Ao) / log (1/2) = t / HL </span>
<span>HL = t / [( log (At / Ao)) / log (1/2) ] </span>
<span>HL = 14.4 s / [ ( log (12.5 / 50) / log (1/2) ] </span>
<span>HL = 14.4 s / 2 = 7.2 seconds </span>
Answer:
of HA is 6.80
Explanation:
Acid dissociation constant (
) of HA is represented as-
![K_{a}=\frac{[H^{+}][A^{-}]}{[HA]}](https://tex.z-dn.net/?f=K_%7Ba%7D%3D%5Cfrac%7B%5BH%5E%7B%2B%7D%5D%5BA%5E%7B-%7D%5D%7D%7B%5BHA%5D%7D)
Where species inside third bracket represents equilibrium concentrations
Now, plug in all the given equilibrium concentration into above equation-
So, 
Hence 
Answer: I think the answer is C. NaCl and H2O
Explanation: I’m not sure tho
Answer:
Below are the statements which are true about the structure of the periodic table:
B: The inner transition elements are placed at the bottom of the periodic table for easy viewing.
D: The distribution of electrons in energy levels is responsible for the shape of the periodic table.
Explanation:
Point A:
As we know that in a periodic table there are 7 period s and 18 groups. So, the number of periods is evidently lesser than the number of groups. But the shape of periodic table is regular and rectangular so point A is false.
Point B:
The inner transition elements or -f block elements are put at the bottom for easy viewing. These are the elements that have the valence electrons only in the f-orbital's. Therefore, they are placed separately at the bottom side of the table so that they can be easily viewed or studied from there. So, point B is true.
Point C:
If we talk about option C, then it is very clear and true that considering a rectangular shape of the periodic table, the groups are vertically arranged and periods are horizontally arranged, therefore it is false.
Point D:
Atoms of all elements have definite electronic distribution in different energy levels like s, p d or f. This is a very prominent feature of periodic tale that elements are divided in specific blocks, s, p, d and f based on their electronic configurations. Therefore, it is true.
Point E:
We also know that no. of metals in a periodic table are more than the no. of non metals like almost 91 out of 118 elements are metals in periodic table. Therefore, the point E "Nonmetals take up more than half the area of the periodic table." is false.
Hope it helps!
