When 3.05 moles of ch4 are mixed with 5.03 moles of o2 the limiting reactant is ch4 + 2o2 → co2 + 2h2o select one: ?

To reiterate the problem, we are asked to find which of the reactants is the limiting one. The reaction is 

CH₄ + 2 O₂ → CO₂ + 2 H₂O

We have an initial amount of 3.05 mol CH₄. Let's see how much of oxygen is required for this:
Theoretical mol O₂ required = 3.05 mol CH₄ * 2 mol O₂/1 mol CH₄ = 6.1 mol

However, the initial amount of oxygen is only 5.03 mol, which is not enough for the theoretical value. Therefore, the limiting reactant is oxygen.

Work done = force ×distancebut force = mass ×gravityand gravity = 10m\s force = 2×10 = 20 work done = 20×3 = 60 joules