What about my chemistry!! Chemistry!!! Hurry, hurry

I believe you have understood the basic knowledge points, but you are not very flexible when using them, which means that you lack practice and cannot use them proficiently.

It is recommended to do some targeted exercises, for example, if you have not learned the part of molecules, atoms, and ions well, then find the relevant topics of that part to do, which will improve the efficiency a lot.

In addition, it is recommended to find some exam questions, not to do the questions in the reference book, which are only used to help you understand, and there is a gap with the exam questions.

Review more. I look at the reference material when I buy it.

Find a tutor and make up for it.

In fact, there is no need to worry, even if the grades are good, and the exam is not ideal, this is caused by pressure, you are still the third year of junior high school, what a good time for me, I didn't experience too many exams, I was very bored before the exam, you relax as much as possible, you said that you don't know the most basic, in fact, it is not necessarily that you won't, you calm down, take a closer look at the chapters that are relatively unfamiliar to you, and you don't have to read much, read carefully, the Lord requires meditation, you will find the feeling of writing like a god, after all, chemistry is very simple, good luck, not too anxious, come on for the high school entrance examination.

Now that you know your shortcomings, why not step up your training?

Find and write more similar questions, do it repeatedly, clarify your thinking, find the topic, the most important point is to be sure to integrate the conceptual things, make a question to know his test point, targeted review!

I'll introduce you to a few** (online learning is also good).

The others are also good.

Don't worry, you can go and find the points you are not familiar with and look up on the Internet, and review the omissions more!

Acidic oxides: CO2, NO2, N2O5, SiO2, P2O5, SO2, SO3, CRO3, Mn2O7

Basic oxides: Na2O, MGO, Li2O, K2O, CaO, Bao, CuO, FeO.

Note: Na2O2 is not a basic oxide because O2 is released when it reacts with acids; Al2O3 is an amphoteric oxide because it reacts with both acids and bases to form salts and water.

Acid oxides CO2, N2O5, SiO2, P2O5, SO3, Cl2O7, Mn2O7

Basic oxides Na2O, MGO, CAO

Acid Oxides:

co2，so3,no2,n03

Basic Oxides:

cao,na2o,mgo,al2o3,

Acid oxides: CO2, SO2, SO3, NO, NO2

Basic oxides: Al2O3, Na2O2, MGO, CAO, Feo, Fe2O3

That's basically what they're most commonly used for.

1) 2kClO3==mNO2 (catalyst) ==2kCl+3O2X

Kcl is a solid, obviously, so the mass reduced by the reaction process (is the mass of oxygen generated, let the kclo3 participating in the reaction be xg, from the above reaction formula x, the quality of manganese dioxide, 2) carbon monoxide does not react with the clarified lime water, ca(ho)2 + co2 = caco3 (precipitation) + h2o

x 2g is the same as (1), let the mass of produced carbon dioxide be x, and the solution is x=, so the mass of carbon dioxide in the original mixture is, and the mass of carbon monoxide is.

And if you don't understand, just hi me...

1. The mass reduced in the reaction is the mass of oxygen produced, 20 2kClO3 = ( mnO2 catalyst) 2kCl + 3O2 x potassium chlorate mass, x = 245

Manganese dioxide mass, 20

2. CO + CA (OH) = CACO HA OX 2 CO2 mass, x = 44 2 100

Carbon monoxide mass, 10

1. The reduced mass is the quality of oxygen.

And then according to the chemical equation, you should be able to do this.

The mass of potassium chlorate reduced with 20g is the mass of manganese dioxide.

2. The white precipitate of 2g is the mass of calcium carbonate, and the mass of carbon dioxide can be found according to the chemical equation, and the quality of carbon monoxide is easy to find.

The concentration of NaCl is molar per liter, and the concentration of barium chloride is moles per liter of chloride ionic substance.

The amount of the substance of NaCl is:

The amount of NaCl substance before mixing is concentrated at 4 5 =

The amount of the substance of BaCl2 is:

The amount of BaCl2 before mixing.

Is this question the original one? Huh...

It can be known that there is NaCl and some barium chloride after mixing. So.

1）n（cl)=4+

The mass concentration of the matter is.

It can be known that there is NaCl and some barium chloride after mixing. So.

1）n（cl)=4+

The mass concentration of the matter is.

a.According to "removing 2 hydrogen atoms from a hydrocarbon molecule to become a carbon-carbon double bond is an endothermic reaction", the dehydrogenation of cyclohexene to 1,3-cyclohexadiene is an endothermic reaction, and the hydrogenation of 1,3-cyclohexadiene to cyclohexene should be exothermic. A error.

b.According to "1,3-cyclohexadiene loses 2 hydrogen atoms to become benzene is an exothermic reaction", it can be seen that the hydrogenation of benzene to 1,3-cyclohexadiene is an endothermic reaction, but from the A solution, we know that the hydrogenation of 1,3-cyclohexadiene to generate cyclohexene is exothermic, and the hydrogenation of cyclohexene to cyclohexane is also exothermic, and it is difficult to say whether the total reaction is endothermic and exothermic. b may be wrong.

c.Generally speaking, the lower the energy of matter, the more stable it is. The loss of 2 hydrogen atoms of 1,3-cyclohexadiene into benzene is an exothermic reaction, indicating that the energy of benzene is lower, and benzene is more stable than 1,3-cyclohexadiene. c error.

d.According to the C explanation, you know that D answers correctly.

Hydrogenation of cyclohexadiene, if the formation of cyclohexane should be an exothermic reaction, and the alkane is more stable than alkene, so the hydrogenation of a wrong benzene to produce cyclohexane should be an exothermic reaction, and the alkane is more stable than benzene, so B is wrong and C is of course wrong.

Phenylcyclohexadiene is stable and helps d correctly.

The removal of 2 hydrogen atoms from a hydrocarbon molecule to become a carbon-carbon double bond is an endothermic reaction, which in turn is exothermic.

1,3-cyclohexadiene loses 2 hydrogen atoms to become benzene which is an exothermic reaction and is not mentioned. Benzene and cyclohexane.

B is a closed container and the quality does not change.

The volume does not change. The density is constant no matter how much you toss inside.

So it's not right

h2so4+nh3=nh4hso4

It is well absorbed with sulfuric acid.

The role of carbon tetrachloride.

It is to control the ammonia rate.

Try to slow it down.

Allow the gas to be fully absorbed.

8 Question y can be oxygen.

It can also be sulfur.

If it is oxygen, whether it is oxygen or sulfur, the oxidation is not as good as F.

So C is right.

If you don't understand, please ask.