Given the reaction system in a closed container at equilibrium and at a temperature of 298 k:
n2o4(g) < ==> 2no2(g)
the measurable quantities of the gases at equilibrium must be
(1) decreasing (3) equal
(2) increasing (4) constant

The measurable quantities of the gases at equilibrium must be constant

Explanation:

Measurable quantities for the gases at equilibrium includes rate of formation of , rate of formation of , pressure of and pressure of .

At equilibrium, rate of forward reaction is equal to rate of reverse reaction.

Rate of forward reaction infers rate of formation of and rate of backward reaction infers rate of formation of .

As rate of formations from both direction are equal therefore pressure of both gaseous species remains constant.