The correct number of significant figures and digits is 3
The concentration of HCl is equal to 2.54mol/L.
<h3>Mole calculation</h3>
To solve this question, one must use the molarity calculation, which corresponds to the following expression:

Thus, to find the molarity of the sample, the following calculations must be performed:



So, 0.00254 moles were added per 10ml, so we can do:

So, the concentration of HCl is equal to 2.54mol/L.
Learn more about mole calculation in: brainly.com/question/2845237
Mg + 2H(NO)3 ⇒ Mg(NO3)2 + H2
Answer:
n₂ = 2.55 mol
Explanation:
Given data:
Initial number of moles = 0.758 mol
Initial volume = 80.6 L
Final volume = 270.9 L
Final number of moles = ?
Solution:
Formula:
V₁/n₁ = V₂/n₂
V₁ = Initial volume
n₁ = initial number of moles
V₂ = Final volume
n₂ = Final number of moles
now we will put the values in formula.
V₁/n₁ = V₂/n₂
80.6 L / 0.758 mol = 270.9 L/ n₂
n₂ = 270.9 L× 0.758 mol / 80.6 L
n₂ = 205.34 L.mol /80.6 L
n₂ = 2.55 mol