2X(？ )+Y(？ )? Answer? Z(g)

MOQ: 2? 20

Transformation quantity: 2x? x？ cut down on

Balance: 2-2x? 2 x axis

From (2-2x): (2-x): AX = 1: 3: 2, x=0.8 and a= 1, so a is wrong;

B if both x and y are gases, the density of the mixed gas is constant. As shown in the figure, if the volume is constant and the gas density increases, solid or liquid should participate in the reaction to generate gas, so B is correct;

C. If both X and Y are gaseous, the pressure of the reaction I system is greater than that of the reaction II system, and the reaction I can be regarded as increasing the pressure on the basis of II and shifting the equilibrium to the reaction direction, then the transformation I > II, so C is wrong;

D if x is a solid and y is a gas, the amount of gas is the same before and after the reaction, and the pressure is unchanged. The pressure in Figure 2 is equal to that in Figure 1, so the time from start to balance in I and II is: I = II, so D is wrong;

So choose B.