I would personally say C. Energy only...
Answer:
130ml of HCl(36%) in 4.90L solution => pH = 1.50
Explanation:
Need 4.90L of HCl(aq) solution with pH = 1.5.
Given pH = 1.5 => [H⁺] = 10⁻¹·⁵M = 0.032M in H⁺
[HCl(36%)] ≅ 12M in HCl
(M·V)concentrate = (M·V)diluted
12M·V(conc) = 0.032M·4.91L
=> V(conc) needed = [(0.032)(4.91)/12]Liters = 0.0130Liters or 130 ml.
Mixing Caution => Add 131 ml of HCl(36%) into a small quantity of water (~500ml) then dilute to the mark.
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<h2 /><h2 /><h2><u>Solution </u><u>3</u><u> Is The Most Concentrated</u></h2>
<h3>S1:</h3>
M = m/v
= 100ml ÷ 2 spoons × 100%
= - 5,000 μg/ppb³
= <u>50% Diluted</u>
<h3>S2:</h3>
M = m/v
= 200ml ÷ 5 spoons × 100%
= - 4,000 μg/ppb³
= <u>40% Diluted</u>
<h3>S3:</h3>
M = m/v
= 300ml ÷ 6 spoons × 100%
= - 5,000 μg/ppb³
= <u>50% Diluted</u>
<h3>S4: </h3>
M = m/v
= 600ml ÷ 8 spoons × 100%
= - 75,000 μg/ppb³
= <u>75% Diluted</u>
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Amount of silver nitrate taken = 269.μmol 
Volume of the solution = 300. mL
Concentration of a solution is generally expressed in terms of molarity. Molarity is defined as the moles of a substance present per liter of the solution.
We want the concentration in millimoles/L.
Converting μmol to millimol solute:
μ
= 0.269 millimol
Volume from mL to L: 
Therefore concentration of the chemist's solution = 
