I’m really sorry I need points I hope you find an answer
Answer:
For quick facts use reference materials such as encyclopedias, almanacs, or dictionaries. For credible and reputable information, use online databases of academic journals, or peer-reviewed journal articles that are written by scholars and researchers for a specific discipline.
Correct answer is 
.
Phosphoric acid is a polyprotic acid having 3 acidic hyrdogen therefore it will have 3 pka values.
The equations for the release of acidic hydrogen can be written as:
From the pka values we can judge the idea of pH as using Henderson-Hasselbalch Equation, we get the relation between pH and pka.
Using the following equation, relation of pH and pka is
![pH=pka+log\frac{[A^-]}{HA}](https://tex.z-dn.net/?f=pH%3Dpka%2Blog%5Cfrac%7B%5BA%5E-%5D%7D%7BHA%7D)
Using this equation, we can find that the equation having pka= 2. 14 is closest to the pH=3.2 so the ionic form in this equation will be dominant at the same pH.
Therefore at pH=3.2 the ionic form of 
is dominant.
Thermosoftening plastics melt when they are heated.This means that they can be recycled , which involves melting them before making a new product. Thermosoftening plastics do not have covalent bonds between neighbouring polymer molecules, so the molecules can move over each other when heated and the plastic melts.
Answer: caffeine is a compound.
Explanation:
1) As stated c<span>affeine contains hydrogen, carbon, nitrogen, and oxygen atoms in a fixed ratio.
2) The definition of compound is a pure substance formed by chemical bonding of two or more fifferent elements. That means a defined ratio of the elements in the compound, which conferes uniform and equal properties to every part of the compound.
Some examples of compounds are salt (NaCl), water (H2O), vinegard (CH3 COOH).
A mixture combines several elements or compounds, not bonded by chemical bonds but mixed in ratios which may vary.
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