A, B, C, D, H2O

ABCDs generally have elements such as C, H, O, and if they are metals, they may be Na, Fe, Mg, and the like. In short, it depends on the situation. You can take a look at this kind of topic and get familiar with the rules of this kind of topic.

There are not many equations for a+b===c+d+water, one of which should be set first and then the other elements should be deduced according to the other conditions given.

Also, it is necessary to remember some substances with special characteristics (very important), such as: gas, then you have to think of NH4 compounds, etc., and what are the precipitates, etc., these will be in many questions, you just need to remember these characteristic compounds).

For this kind of problem, you have to think of some common elements such as: c, h, o, these are almost in the same problem, and then use these as assumptions What if it is c

a b c d water Then you should first think that maybe the reaction of alkali and acid will produce water, and then judge the problem according to other prompts.

Also, it is necessary to remember that some substances with special characteristics (very important) such as the production of gases should be thought of.

NH4 compounds, etc., and what are the precipitates, etc., and there are many of these questions, you just need to memorize these characteristic compounds).

That's all I can say from your question, and I can't say anything else.

You give two of the same conditions, A and D, and the action can produce B, which is not a repetition.

a、b、c、d

Group 1: c; co；co2；o2

Group 2: cuo; co2；c；co

Group 3: FEO; co2；c；co

Group 4: Fe2O3; co2；c；co

Group 5: Fe3O4; co2；c；co

Group 6: NAOH; na2co3；nahco3；CO2 Group 7: Ca(OH)2;caco3；ca(hco3)2；co2

a b c d can be sodium, oxygen, sodium oxide, sodium peroxide; carbon, oxygen, carbon monoxide, carbon dioxide;

Now I can only come up with these two.

Is it known that A and D can produce B, B and D can produce C, and A and C can produce B?

Solution: a b c d Group 1: c; co；co2；o2

Group 2: Metal oxides such as cuo; co2；co；c (I made a mistake on the second floor!) Group 3: c; co；co2；h2o

Group 4: NAOH; na2co3；nahco3；CO2 Group 5: H2S; s；so2；o2

Group 6: NH3; n2；no；O2 (ammonia is burned in pure oxygen to produce nitrogen, catalytically oxidized to obtain NO).

Group 7: ALCL3; al（oh）3 ；naalo2 ；naohps: upstairs is not easy to achieve a and c action can generate b, such as it!

In total, there were 2 A who participated in the reaction. b has 6.

In this way, the product also has 2 A, 6 B, so the chemical imitation of C is slow ab32 C's are 2 ab3s

There is no standard answer to this, as long as A is a monobasic acid, you can push out what salt B is, for example, A is HCl, B is NaCl, A is Hno3, B is Nano3, A is HBR, B is NABR, but the molecular weight difference between A and B is fixed, B-A=Na-H=23-1=22

In total, there were 2 A who participated in the reaction.

b has 6. In this way, only the oak makes the product also have 2 Zen volt a, and refer to 6 b so c. Chemical formula.

ab32 C

That's 2 ab3s

There is a mistake on the first floor.

a：no2 b：hno3 e：no

The reaction equation between a and water: 3NO2+H2O=2HNO3+NO

1) Substance C is CO2, electronic formula. The computer can't type; Chemical formula of D: NaHCO3

2) 4H+ (hydrogen ion) + NO3- (dilute) + FE = Fe3 + (iron ion) + NO (gas symbol) + 2H2O

a：c b：co2 c：ca(hco3)2 d：caco3 e：h2

Chemical formula of a: c

The ionic equation for the reaction of C with X: 2(Ca2+) + 2HCO3 - +2OH - = 2CaCO3 (white precipitate) + 2H2O

The chemical formula of C is A2B3.

2a2+3b2=2c

Divide A:4B:6 on the left by 2 to get A2B3, so the chemical formula of C is A2B3.

b3a2

3 and 2 are the lower corners.

n2o3 bar.,After looking at it for a long time, it seems that only this one is in line.。