10.00 mL sample of aqueous HCl requires 31.00 mL of 0.0900 M NaOH to reach the endpoint. What is the molar
concentration of HCl.

Molar concentration of HCl = 0.279 M

Explanation:

Given data:

Volume of NaOH = 31.00 mL ( 31/1000 = 0.031 L)

Molarity of NaOH = 0.0900 M

Volume of HCl = 10.00 mL (0.01 L)

Molar concentration of HCl = ?

Solution:

Chemical equation:

NaOH + HCl    →   NaCl + H₂O

Number of moles of NaOH:

Number of moles = Molarity × volume in L

Number of moles = 0.0900 mol/L  × 0.031 L

Number of moles = 0.00279 mol

For one mole of HCl one mole of NaOH is required.

Number of moles of HCl = 0.00279 mol

Molar concentration of HCl = 0.00279 mol / 0.01 L

Molar concentration of HCl = 0.279 M

idk

explanation:

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.