Some junior high school chemistry problems, please help, you can get extra points if you are satisfi

1) o si al fe generally only takes the first 4 exams, which can only be memorized.

2) The most abundant nitrogen in the air is nitrogen, so it can only be N3)d Such as O2, O3 is composed of a mixture.

4) Elemental, elemental, atomic, elemental, compound, molecule.

This requires you to figure out what is elemental and what is a compound, and read the book for yourself, which has all of them.

5) The most fundamental difference between elements is the difference in the number of protons, that is, the number of nuclear charges.

1 Oxysilicone, aluminum, iron and calcium (raising turtles and iron covers).

2 The volume content is nitrogen at most (probably molar mass ......3 d4 Iron is a pure substance composed of the same kind of elements, belonging to the elemental ——, composed of iron-atoms; Carbon dioxide is a pure substance composed of different kinds of elements, belonging to compounds, and is composed of carbon dioxide.

5 The number of protons determines the kind of substance.

1、o si al fe ca

2. N12 questions are memorized by rote, and the main group elements of the periodic table can be memorized, not to mention these few.

3, d because there may be allotropes (such as diamond and graphite) 4, elements, elementals, atoms.

Elements, compounds, molecules.

If you ask why you fill in this, it means that you don't have a good grasp of the basics, read more books.

5. Carbon dioxide is composed of carbon and oxygen.

Because the original classification of elements is based on the number of protons, the same number of protons is the same element.

1 Oxysilicone, aluminum, iron, calcium These 5 words are not difficult to memorize, we all came over like this......It often appears in inference questions, so keep it in mind.

2 The most abundant content is nitrogen Scientists have summed it up after n more experiments, how can there be why, back

3 d (a answer, may be composed of allotropic forms, such as O2 O3,) 4 Iron is a pure substance composed of the same species (elements), which is elemental, and is composed of iron (atoms); Carbon dioxide is a pure substance composed of different kinds of elements, belonging to compounds, and is composed of carbon dioxide. This is the only way to answer this question......

5 The number of protons determines the kind of substance.

1. Oxygen, silicon, aluminum, iron. It's in the textbooks).

To remember the composition of air: nitrogen is followed by oxygen, carbon dioxide, noble gases, etc.

d, element, element, atom, element, compound, molecule.

1.New energy, new materials, the development of drugs, and many other uses that are beneficial to human development. Expand the living space of human beings and promote the quality of human life.

2.Clothing. We wear beautiful synthetic fiber clothing to make people look more beautiful and improve the quality of life.

Food. Chemical flavorings, sodium citrate, anticoagulants, and more.

Live. New houses, such as houses that can automatically change the temperature, are warm in winter and cool in summer.

Yes. People use new energy sources such as solar cars, panels, etc.

3.123457 I'm not sure, there are physical and chemical relationships, but the main thing may not be clear.

a Option is based on basic knowledge of chemistry. Table salt does not produce chlorine gas.

1 Man-made fiber, elastomer, ceramic, plastic.

2 Clothes use a lot of synthetic materials, salt iodization, cement to build houses, car fuel 3 1, 2, 3, 4, 5, 7 (uncertain) 4ab

1 ceramic, glass, rubber.

2 Clothes Chemical dyeing items with beautiful colors make our clothes more glamorous, easier to show style or culture, and facilitate the communication of culture.

3 Select all. 4 a

1 Plastic, man-made fiber, elastomer.

2.Many of the materials used in clothes are synthetic, such as polyester, baking soda used in steamed buns, natural gas, cement paint, and gasoline.

3. Select all, which is mentioned in chemistry books.

4 A The electrolyte of salt solution is these three (the knowledge of the first year of high school) to make 84 disinfectant.

1.Creation of new elements such as technetium, promethium Synthesis of new compounds Creation of new conditions for the creation of new reactions and new substances (I can't think of it).

2.Clothing, chemical fiber clothing, food, chemical condiments such as sodium citrate, plywood, hydrogen vehicles 3: all (personal opinion).

4: ab (I don't know if it's a single choice or multiple choice).

1.New energy, new materials, drugs.

Look at the encyclopedia, a little uncertain.

A:Co,CH4 combustion will produce H2O, CO2B:Co combustion will produce CO2 H2 combustion will produce H2OC:CH4 combustion will produce H2O,CO2

D:N2 does not burn at normal temperatures. At high temperatures, N2O can be generated, which increases the weight of NaOH.

Elimination solves this problem.

Anhydrous copper sulphate turning blue indicates that the product contains aqueous vapor and hydrogen in the gas.

The increase in the mass of sodium hydroxide solution indicates that the product contains CO2 and the gas contains element C.

As long as the gas does not contain elements H and C, the answer is the answer.

Option d only has the element h, the correct solution.

D, it's hard to explain to you. Fill it in first.

D must have carbon dioxide, and D can only produce water, water is all absorbed by a sufficient amount of anhydrous copper sulfate, nitrogen cannot be burned in oxygen, so D is chosen.

It cannot be d, because the anhydrous copper sulphate turns blue indicates that there is hydrogen in the generated water, and the increase in the mass of sodium hydroxide indicates the formation of carbon dioxide, which indicates the presence of carbon, while there is no carbon in d.

na2co3+2hcl=2nacl+co2↑+h2o106 117 44x y

x = y = mass fraction of sodium chloride in solids (

Solid matter (

na2co3+2hcl===2nacl+h2o+co2106 117 44x y

x=sodium chloride mass fraction=

y=mass of solid matter=

na2co3+2hcl=2nacl+h20+co2↑106 117 44（ (

The mass fraction of sodium chloride is (200-m(Na2CO3)g) 200g= The mass of the remaining solid matter is.

A of the reaction = 25-10 = 15

The mass of d = 15 + 5 - 11 = 9

aa + bb ==cc + cd

30a 20b 44c 18d

From the above ratio, we can get a:b:c:d=2:1:1:2, so the answer is c

2. Before the reaction, there are 4 conjoined small black balls, which is 4 in A.

The large conjoined gray ball has 1, which means that B has 1.

After the reaction, there is 1 conjoined small black ball, which means that there are only 3 A participating in the reaction.

There are 2 gray balls with 3 small black balls, which means that C has 2.

Then the reaction is 3a+b==2c

According to the mixture after the reaction, 10g of A is known, and 25g of A participates in the reaction, and 15g of A and 5g B are exactly reacted into 11g of C and 9g of D. According to the molecular mass ratio of A and B is 30:20, it should be equipped with 2 A molecules to participate in the reaction to meet the 30x2:

So the molecular coefficient of A is 2 and the molecular coefficient of B is 1. In the same way, because the relative molecular mass ratio of C to D is 44:18, 11 g of C and 9 g of D are generated, so 2 B molecules are equipped to participate in the reaction, then 44:

11 = 18x2: 9 = 4, so the propylene coefficient is 1 and the butyl coefficient is 2

Get option C.

The reaction is: A + B = C + D, and the actual amount of A reaction is 25-10 = 15g, that is, the ratio of the mass of each substance in the reaction is 15:5:

11:9, while their relative molecular mass ratio is 30:20:

44:18, we get 2a+b=c+2d

nano3nano2

We can see that both n and na are 1:1 combined.

So the cover na:n=23:14

That is, the content of NA is 20 14 23=

The rest is the amount of hail of を.

That is, the oxygen content is 100%.