Answer:
Canonical structures of a chemical specie explain its observed properties from a valence bond theory perspective.
Explanation:
Resonance is a valence bond concept introduced by Linus Pauling to explain the observed properties of certain chemical species such as bond lengths, bond angles, bond order , etc.
There are certain chemical species for which a single chemical structure does not suffice in explaining its observed properties. For instance, the bond order in CO3^2- is about 1.33. Its bond length, shows that the C-O bond present in CO3^2- is neither a pure C-O single bond nor a pure C-O double bond. Hence the structure of CO3^2- is 'somewhere in between' three contributing canonical structures as shown in the image attached to this answer. The resonance structures of NO3^- are also shown.
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The acid dissociation constant, Ka, is an equilibrium constant that measure the strength of an acid. It is a ratio of the concentration of the products (salt and water) and the reactants (acid). The higher the Ka, the more tendency it is to favor the product side, which means more tendency to donate H+ ions. This is exactly the definition of a strong acid (high H+ ionized).
Thus, the answer is letter D.
The reaction of acetic acid with sodium hydroxide is:

The ratio of A-/HA is calculated as follows:
According to Henderson Hasslebach equation:
![[A-]/[HA] = 10^p^H^-^p^K^_a](https://tex.z-dn.net/?f=%5BA-%5D%2F%5BHA%5D%20%3D%2010%5Ep%5EH%5E-%5Ep%5EK%5E_a)

The total concentration of HA and A- = 2.0 L * 0.25 M = 0.5 mol.
![[ A- ]+ [ HA ]= 0.5](https://tex.z-dn.net/?f=%5B%20A-%20%5D%2B%20%5B%20HA%20%5D%3D%200.5)
![[ A^- ] = 0.5 – [ HA]](https://tex.z-dn.net/?f=%5B%20A%5E-%20%5D%20%3D%200.5%20%E2%80%93%20%5B%20HA%5D)
[ HA] = 0.156 mol and [ A- ]= 0.343 mol
Total of 0.5 moles of acetic acid is required:

HA = 30.0 g acetic acid
Conversion of 0.343 moles of the acetic acid to acetate can be performed by adding NaOH

= 343 mL
Thus, 343 mL of 1M NaOH is required
Answer:
D: chain of volcanoes circling the Pacific Basin
Explanation: