Two experiments were performed involving the following equilibrium. the temperature was the same in both experiments. h2(g) + i2(g) 2hi(g) in experiment a, 1.0 m i2 and 1.0 m h2 were initially added to a flask and equilibrium was established. in experiment b, 2.0 m hi was initially added to a second flask and equilibrium was established. which of the following statements is always true about the equilibrium concentrations?
a.[h2] equals [hi] in experiment a.

b.[hi] equals 2[h2] in experiment a.

c.[hi] in experiment a equals [hi] in experiment b.

d.[hi] in experiment a equals 1/2[i2] in experiment b.

Answer : The correct option is, (C) [HI] in experiment A equals [HI] in experiment B.

Explanation :

For experiment A :

The given balanced equilibrium reaction is,

In experiment A, when we start with 1 mole of hydrogen & 1 mole of iodine gas then it combines to form HI. If this was a completely one-way reaction then it can form 2 moles of HI.

For experiment B :

The given balanced reverse equilibrium reaction is,

In Experiment B, when we start with 2 moles of HI then it breaks into hydrogen & iodine. If this was a completely one-way reaction then it can form 1 mole of hydrogen and 1 mole of iodine gas.

As we know that equilibrium can be obtained both from reactant and product side.

From the above we conclude that in both the experiments, the same concentration ratio is approached but from an opposite directions. In the end, the concentration of HI will be the same for both the experiments.

Hence, the correct option is, (C) [HI] in experiment A equals [HI] in experiment B.