Answer:A) cotton
A fiber if available in trace or appropriate amount can link a suspect to a crime.Solubility is a preliminary test performed for identification of the type of fiber. In this method small amount of fiber evidence is dissolved in the suitable solvent to identify it's type. Some fibers completely get solublize in the solvent, some get partially soluble and other can only change their color or do not dissolve at all.
According to the given situation, the fiber dissolved in hydrochloric acid can be cotton. As the fibers of cotton are soft and slender and will get easily solubilize in hydrochloric acid.
<u>Answer:</u> The tree was burned 16846.4 years ago to make the ancient charcoal
<u>Explanation:</u>
The equation used to calculate rate constant from given half life for first order kinetics:
where,
= half life of the reaction = 5715 years
Putting values in above equation, we get:
Rate law expression for first order kinetics is given by the equation:
![k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B2.303%7D%7Bt%7D%5Clog%5Cfrac%7B%5BA_o%5D%7D%7B%5BA%5D%7D)
where,
k = rate constant = 
t = time taken for decay process = ? yr
![[A_o]](https://tex.z-dn.net/?f=%5BA_o%5D)
= initial amount of the sample = 100 grams
[A] = amount left after decay process = 13 grams
Putting values in above equation, we get:
Hence, the tree was burned 16846.4 years ago to make the ancient charcoal
You must use 64.43 g H₂O.
<em>Balanced chemical equation</em>: H₂O + CO₂ → H₂CO₃
<em>Moles of CO₂</em> = 157.35 g CO₂ × (1 mol CO₂/44.01 g CO₂) = 3.5753 mol CO₂
<em>Moles of H₂O</em> = 3.5753 mol CO₂ × (1 mol H₂O/1 mol CO₂) = 3.5753 mol Fe
<em>Mass of H₂O</em> = 3.5753 mol H₂O × (18.02 g H₂O /1 mol H₂O) = 64.43 g H₂O
<span>The problem has to do with oxidation states of the matter. The oxidation state of oxygen will always be -2 with the exception of peroxides which will have a state of -1. The overall balanced state of chemical compounds will be 0, so the oxidation state of Mn in MnO2 will be +4. The oxidation state of MnO4- will then be +7 to balance out to the negative one charge. The state change from +4 to +7 is 3, thus three electrons have to be lost in order for this to happen; a loss of a charge of -3 results in an increase of charge of 3. Oxidation is always the process of 'losing' electrons.
</span><span>E] MnO2(s) MnO4-(aq</span>
