<h3>Question :</h3>
Which of the following sources could not be used to obtain the DNA of a person lost in a mass disaster?
- used and unwashed clothing or bed sheets
- food found in the victim's refrigerator
- sunglasses regularly used by the person
- a toothbrush used by the person
<h3>Answer :</h3>
food found in the victim's refrigerator could not be used to obtain the DNA of a person lost in a mass disaster.
So, correct answer is 2nd one.
Answer:
0.0922 M
Explanation:
The problem first states that the titration is made using NaOH, and later asks about the addition of KOH. I'm going to assume NaOH was used throughout the whole problem. The result does not change if it was KOH instead.
The reaction that takes place is:
- HClO₄ + NaOH → NaClO₄ + H₂O
First we <u>calculate how many HClO₄ moles are there in the sample</u>, using the <em>given molarity and volume</em>:
- 0.624 M * 13.0 mL = 8.11 mmol HClO₄
Then we <u>calculate how many NaOH moles were added</u>:
- 0.258 M * 15.0 mL = 3.87 mmol NaOH
Now we calculate how many HClO₄ remained after the reaction:
- 8.11 - 3.87 = 4.24 mmol HClO₄
As <em>HClO₄ is a strong acid</em>, 4.24 mmol HClO₄ = 4.24 mmol H⁺
Finally we <u>calculate the molarity of H⁺</u>, using the<em> calculated number of moles and final volume</em>:
- Final volume = 31.0 mL + 15.0 mL = 46.0 mL
- 4.24 mmol / 46.0 mL = 0.0922 M
Answer:
(C) Decomposition reaction
Explanation:
A decomposition reaction is a chemical reaction in which a single compound breaks down into two or more compounds or elements.
<u>in this example </u>
- 2KClO₃(s) ->2KCl (s) + 3O₂ (g)
Potassium chlorate (KClO₃) decomposed to two smaller compounds KCl and O₂ gas.
So, the right choice is (C) Decomposition reaction
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