20题到22题,
3个回答

20,4.9/98= 0.05mol 0.05*18=0.9g 0.05*4*18=3.6g

21,3:2:1 0.3*58.5+0.2*95+0.1*133.5

22,2.4/40=0.06mol 0.06/0.3=0.2mol/l 0.2mol/l 0.2*0.03=0.006mol 0.006/0.12=0.05mol/l 0.006*2/0.1=0.12L=120ml