The chemical equation for the reaction is ,
2 Na + Cl₂ → 2 NaCl
Before applying stoichiometry, first you will have to find the moles of Cl₂ at given conditions using Ideal gas equation.
n = P V / R T
As, temperature is not given, so put standard Temperature i.e. 273 K, or if you are provided with it simply put its value So,
n = (1.15 atm × 2.6 L) ÷ (0.0821 atm.L.mol⁻¹.K⁻¹ × 273 K)
n = 0.133 mol of Cl₂
Now,
According to Balance equation,
1 mole Cl₂ required = 2 moles of Na
So,
0.133 mol Cl₂ will require = X moles of Na
Solving for X,
X = (0.133 mol × 2 mol) ÷ 1 mol
X = 0.266 moles of Na