.5 mols
Assuming that your 2.0 m is an M for molarity
I used the formula M=number of mold/L
Converted 250mL to .250L by dividing by 1000
A is your answer.
On the periodic table the atomic number is the number of protons inside the nucleus.
Mass of H₂ needed to react with O₂ : 1.092 g
<h3>Further explanation</h3>
The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight / volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.
Reaction
O₂(g) + 2H₂(g) → 2H₂O(g)
mass of O₂ : 8.75 g
mol O₂(MW=32 g/mol) :

From the equation, mol ratio of O₂ : H₂ = 1 : 2, so mol H₂ :

Mass H₂ (MW=2 g/mol) :

Answer:- HBr is limiting reactant.
Solution:- The given balanced equation is:

From this equation, There is 2:6 mol or 1:3 mol ratio between Al and HBr. Since we have 8 moles of each, HBr is the limiting reactant as we need 3 moles of HBr for each mol of Al.
The calculations could be shown as:

= 24 mol HBr
From calculations, 24 moles of HBr are required to react completely with 8 moles of Al but only 8 moles of it are available. It clearly indicates, HBr is limiting reactant.
Answer: potassium nitrate
hope this helps