Answer:
Measure 74.2 g Na2CO3 and add H20 until the final homogeneous solution has a volume of 7.00 L
Explanation:
The best procedure is
Mole of

= 0.700 mol
The mass of

= 74.2 g
So as per the above calculation, the option 3 is correct as the solution volume is 7.00 L so the same is to be considered
hence, all other options are wrong
The empirical and molecular formulas will be
and
respectively.
<h3>Empirical and molecular formula</h3>
The compound contains C, H, and O.
C = 61.15/12 = 5.0958
H = 5.3/1 = 5.3
O = 31.55/16 = 1.9719
Divide by the smallest
C = 2.6
H = 2.7
O = 1
Thus, the empirical formula is 
Empirical formula mass = (12x5) + (1x5) + 16x2 = 97
n = 152.15/97 = 2
The molecular formula is 
More on molecular and empirical formulas can be found here: brainly.com/question/14425592
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I think the answer is codominant??
Answer
pOH = 4.1
Explanation
<em>Given:</em>
pH = 9.9
<em>Required</em>: The concentration of OH-
Solution
pH + pOH = 14
9.9 + pOH = 14
pOH = 14-9.9
pOH = 4.1