Ta co Mna2co3.h2o = ( 23.2+12+3.16).(3.2+16)=3388

ta co %mNa2co3 = M.100/338= 106.100/3388= 3,13%

->mNa2co3= 3,13.33/100 = 106 g

-> khoi luong cua na2c03 trong 2kg hh la 106/1000.2=0.212 kg

ta co 2*(m-5) khac 0

-> 2m -5 khac 0

-> 2m khac 5 -> m khac 5/2

a , ta có pthh4 Al +3O2

​->2Al2O3 b, theo đề bài ta có nO2= 3.36/22.4=0.15 mol Theo pthh nAl=4/3nO2= 4/3.0.15= 0.2 mol -> mAl = 0.2*27=5.4 g. c, theo đề bài ta có nO2= 2.24/22.4=0.1 mol. Theo câu a ta có mAl =5.4 g -> nAl= 5.4/27=0.2 mol theo pthh ta có nO2=0.1/3 mol < nAl=0.2/4 mol Vậy chất dư là Al . Ta có số mol Al sau pư = 4/3 nO2 = 4/3*0.1= 2/15 mol -> số gam Al dư sau pư là mAl= (0.2 - 2/15)* 27= 1.8 g

Mark the letter A, B, C, or D on your answer sheet to show the underlined part that needs correction

Pointing in someone is usually considered impolite but it is acceptable when a teacher wants to get someone’s attention in class.

A. Pointing in 

B. impolite 

C. when 

D. to get