a mole is defined as the amount of substance that contains as many atoms, molecules, icons, electron or any other elementary entities as there are exactly 12 gm of. of carbon atoms. the number of 12 gm of. Is called Avogadro's number
A variable that is not being directly tested during an experiment should be independent
The answer to this question is 2 and 3
A, b, c, d, e, f, all of them should be checked
A titration is defined as 'the process of determining the quantity of a substance A by adding measured increments of substance B, the titrant, with which it reacts until exact chemical equivalence is achieved (the equivalence point)'.
The Molarity of the HCl Solution requires the addition of 24.6 mL of titrant is 0.0836 M (to 3 significant figures)
<h3>What is Titrant?</h3>
A reagent solution of precisely known concentration that is added in titration
Given reaction HCl + NaOH ===> NaCl +
neutralization reaction
Note that the mole ratio is 1:1 meaning that 1 mole HCl reacts with 1 mole NaOH to produce 1 mole NaCl and 1 mole 
Find moles of NaOH used:
18.45 ml x 1 L/1000 ml x 0.085 mol/L = 0.002091 moles NaOH used
This meant that there must be 0.002091 moles of HCl present in the 25.0 mls.
We want to find the molarity (M) which is moles HCl/liter of solution. We know the moles, and we also know the liters of solution (25.0 mls x 1 L / 1000 mls = 0.025 liters)
M = 0.002091 moles HCl / 0.025 liters = 0.08364 M = 0.0836 M (to 3 significant figures)
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