Given the equation representing a system at equilibrium:
N204(g) = 2NO2(g)
Which statement describes the concentration of the two gases in this system.
1) The concentration of N2O4(g) must be less than the concentration of NO2(g)
2) The concentration of N2O4(g) must be greater than the concentration of NO2(g)
3) The concentration of N2O4(g) and the concentration of NO2(g) must be equal
4) The concentration of N2O4(g) and the concentration of NO2(g) must be constant

The concentration of N2O4(g) and the concentration of NO2(g) must be constant

Explanation:

A system at equilibrium as described by this equation

N2O4(g) <> 2 NO2 (g), shows that the concentration of N2O4 (g) and the concentration of NO2 (g) is constant. This is true because the rate at which the forward reaction is occurring that is N2O4 giving NO2 is the same as the rate at which the reverse reaction is occurring. At this point, the concentration of both substances is not changing but constant. In this type of reaction, reactions are still occurring in the system but there is no overall change in the  concentrations of the substances involved.

When we plot a concentration and time graph, at a point in time we can see that the concentrations does not change (remains constant)

At any given time t:

Rate (forward) = k[N 2 O 4] = - Δ[N 2O 4] / Δ t

Rate (reverse) = k[NO 2]2 = - Δ[NO 2] /  Δ t

they it depends on if one believes about radioactivity, they make a geiger counter beep but maybe it was going to beep anyway electronics do wierd things all the time or it was programmed to beep near certain metals.

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer