If a solution containing A+ ions and a solution containing B- ions have just been mixed and [A+][B-] is greater than Ksp of AB, .

the solution is unsaturated

precipitation occurs

equilibrium does not occur

the solution is concentrated

Explanation:

In the solution of AB , they are split  to give ions as follows

AB ⇄ A⁺ + B⁻

Product of concentration of A⁺ and B⁻ in saturated solution of AB is constant .

This is called Ksp

Ksp = [A⁺] [ B⁻]

If product of concentration of A⁺  and B⁻ exceeds Ksp , the equilibrium shifts to the left side and excess ions come out of solution in the form of precipitate. So second option is the answer.

law of conservation of matter

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !