(1) It can be seen from the image that when the amount of X and Y decreases and the amount of Z increases by 2, X and Y are reactants and Z is product, while △ n (y): △ n (x): △ n (z) = 2.2 mol: 2.1mol: 2.

So, the answer is: x+2 yrz;

(r) A. The concentration at equilibrium depends on the concentration at the beginning of the reaction and the degree of conversion, and can not be used to judge whether the equilibrium state is reached, so A is wrong;

B. When the temperature and volume are constant, the concentration of a certain product will not change, indicating that it has reached an equilibrium state, so B is correct;

C. Because the stoichiometry of the gas is different before and after the reaction, the pressure in the container will not change under the condition of constant temperature and volume, which means that the equilibrium state is reached, so C is correct;

D. Because the stoichiometry of the gas before and after the reaction is different, the average relative molecular mass of the mixed gas will not change when the temperature and volume are constant, which means that the equilibrium state is reached, so D is correct.

So, the answer is: b, c, d;

(2) When the equilibrium is set, the change of the concentration of X is X,

? X+2 years

Start: 1mol/L? 1.tmol/L？ 2

Conversion: x 2x rx

Equilibrium: (1mol/l-x) (1. tmol/l-2x) rx。

Then: rx 1-x+ 1. t-2x+rx× 122% = rt%，

Solution: x=2 mol/l,

Therefore, the molar concentration of x is 1mol/L-2. rtmol/L = 2.7tmol/L .

So the answer is: 2.7 tmol/L.