The acidic substance in vinegar is acetic acid, HC2H3O2 When 4.00 g of a certain vinegar sample was titrated with 0.200 M NaOH, 25.56 mL of the NaOH solution were required to reach the equivalence point. What is the mass percent of HC2H3O2in the vinegar?

7.68%

Explanation:

Let's consider the neutralization reaction between acetic acid and sodium hydroxide.

HC₂H₃O₂ + NaOH → NaC₂H₃O₂ + H₂O

25.56 mL of 0.200 M NaOH reacted. The reacting moles of NaOH are:

0.02556 L × 0.200 mol/L = 5.11 × 10⁻³ mol

The molar ratio of HC₂H₃O₂ to NaOH is 1:1. The reacting moles of HC₂H₃O₂ are 5.11 × 10⁻³ moles.

The molar mass of acetic acid is 60.05 g/mol. The mass corresponding to 5.11 × 10⁻³ moles is:

5.11 × 10⁻³ mol ×  60.05 g/mol = 0.307 g

0.307 g of acetic acid are in 4.00 g of vinegar. The mass percent of HC₂H₃O₂ is:

0.307 g/4.00 g × 100% = 7.68%

im not exactly sure but i think its b!

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.