The ideal gas equation is pV = nRT
From that you can derive several equations, depending on which variables are fixed.
1) When n and T are fixed:
pV = nRT = constant
pV = constant => p1 V1 = p2 V2 => p1 / V2 = p2 / V1 ---> Boyle's Law
2) When n and V are constant:
p / T = nR/V = constant
p / T = constant => p1 / T1 = p2 / T2 ----> Gay - Lussac's Law
3) when n and p are constant
V / T = nR/p = constant
V / T = constant => V1 / T1 = V2 / T2 ---> Charles' Law
4) When only n is constant
pV / T = nR = constant
pV / T = constant => p1 V1 / T1 = p2 V2 / T2 ----> Combined gas law.
There you have the four equations that agree with the ideal gas law.
Answer
Na OH reacts with H Cl and forms Na Cl and H₂O
NaOH + HCl → NaCl + H₂O
Here we can see that 1 mole of NaOH reacting with 1 mole of HCl and forming 1 mole of NaCl and 1 mole of H₂O
when NaOH and HCl are added together in equal amount then they will completely neutralize each other but NaOH is hygroscopic in nature which means it can absorb water from air so it will not be weighted accurately.
hence, for neutralization we will take extra NaOH.
The balanced equation for the above reaction is as follows;
2S + 3O₂ --> 2SO₃
Stoichiometry of O₂ to SO₃ is 3:2
O₂ is the limiting reactant and S is provided in excess. since O₂ is the limiting reactant, the whole amount is consumed in the reaction and amount of product formed depends on amount of limiting reactant present.
Number of O₂ moles reacted- 4 g / 32 g/mol = 0.125 mol
3 mol of O₂ forms 2 mol of SO₃
therefore when 0.125 mol of O₂ reacts number of SO₃ moles - 2/3 x 0.125 mol
Number of SO₃ moles formed - 0.0833 mol
Answer is 4) 0.08 mol