Question

Given the equation representing a system at equilibrium:
2SO2(g) + O2(g) <==> 2SO3(g)
At equilibrium, the concentration of
(1) SO2(g) must equal the concentration of SO3(g)
(2) SO2(g) must be constant
(3) O2(g) must equal the concentration of SO2(g)
(4) O2(g) must be decreasing

Answer 1

Looking at the balanced equation, we can see that the coefficient of SO2(g) is equal to that of SO3(g). Therefore, when at equilibrium, statement (1): the concentration of SO2(g) must equal the concentration of SO3(g) is correct.
Hope this would help :))

Answer 2

Answer: a.  SO2(g) must equal the concentration of SO3(g)

Explanation:

$K _{C} =\frac{[SO_{3} ]^{2} }{[SO_{2}]{2}  . [O_{2} ]}$

The equilibrium constant can be defined as the ratio of the concentration of product and the concentration of reactant and all raise to the power of the respective coefficient.

Here, in the above mention equation, SO2(g) and SO3(g) the concentration is equal in reactant and product side that is 2 .Hence, option A is correct.