Answer:
B and C
Explanation:
When we have to do a buffer solution we always have to choose the reaction that has the <u>pKa closer to the desired pH value</u>. When we find the pKa values we will obtain:
![pKa_1=-Log[6.9x10^-^3]=2.16](https://tex.z-dn.net/?f=pKa_1%3D-Log%5B6.9x10%5E-%5E3%5D%3D2.16)
![pKa_2=-Log[6.2x10^-^8]=7.20](https://tex.z-dn.net/?f=pKa_2%3D-Log%5B6.2x10%5E-%5E8%5D%3D7.20)
![pKa_3=-Log[4.8x10^-^13]=12.31](https://tex.z-dn.net/?f=pKa_3%3D-Log%5B4.8x10%5E-%5E13%5D%3D12.31)
The closer value is pKa2 with a value of 7.2. Therefore we have to use the second reaction. In which 
is the <u>acid</u> and 
is the <u>base</u>. Therefore the answer for the first question is B and the answer for the second question is C.
The mass of 6.12 moles of arsenic (As) is calculated to be approximately 459g.
HOW TO CALCULATE MASS:
The mass of a substance can be calculated by multiplying the number of moles of a substance by its molar mass. That is;
Mass of Arsenic = no. of moles of As × molar mass of As.
According to this question, 6.12 moles of arsenic was given and its molar mass is 74.92g/mol.
Mass of As = 6.12 mol × 74.92g/mol
Mass of As = 459g
Therefore, the mass of 6.12 moles of arsenic (As) is calculated to be approximately 459g.
Learn more about mass calculations at: brainly.com/question/8101390
A hypothesis
-Can be tested
-Is a prediction about the expected outcome of an experiment
-Must be stated in a form that can be either proven or disproven
Your answer is D: All of the above are true
Answer:
Na₂SO₃
Explanation:
We can use the <em>criss-cross method</em> to work out the formula.
1. Write the <em>symbols</em> of the anion and cation.
Na¹⁺ SO₃²⁻
2. <em>Criss-cross the numbers of the charge</em>s to become the subscripts of the other ion (see image).
3. Write the formula with the <em>new subscripts</em>.
Na₂(SO₃)₁
4. Omit all subscripts <em>that are 1.</em>
The formula becomes Na₂SO₃.
