(experimental area of curriculum reform)
(Examination time: 90 minutes, full mark: 100)
Title Volume I Volume II Total
Three four five
score
You can use the relative atomic mass: h:1c:12n:14o:16p: 31s: 32cu: 64.
The first volume (multiple choice questions ***40 points)
The title is 1 23455 6789 10.
answer
The title is11213141516171819 20.
answer
The answers to the first and second questions in the first volume of multiple-choice questions must all be filled in the above table, and those written elsewhere will not be scored.
1. Single choice (* * 15 small questions, 2 points for each small question, 30 points for each small question, and only one option for each small question meets the meaning of the question)
1. In the following life cases, the main process is chemical change:
A. with deep kung fu, the iron pestle is ground into a needle. When the festival comes, fireworks are colorful.
C. when spring comes, the ice and snow melt. D. When the wine is boiled, the room is full of fragrance.
2. The Indian Ocean tsunami polluted the local drinking water. Medical aid workers intend to give some advice to local residents on drinking water treatment. The following suggestions are unreasonable:
A. precipitating suspended particles with alum; B. disinfect with bleach.
C. As long as it is colorless and transparent, you can safely drink it. D. Boil it before drinking.
3. Sudan Red 1 is a coloring additive, which may cause human cancer. Its chemical formula is C 16H 12N2O. The following statement about it is wrong:
This is an organic compound.
B among the elements contained, element c has the highest mass fraction.
C in its molecule, the number ratio of carbon, hydrogen, nitrogen and oxygen atoms is l6: 12:2: 1.
D The mass ratio of carbon, hydrogen, nitrogen and oxygen contained therein is l6: 12:2: 1.
Water is the source of life. The following "water" in life can be regarded as pure:
A. hard water B. tap water C. partially frozen distilled water D. soda water
5. "Application Technology of Ceramic Matrix Composite with High Temperature Resistance, Long Life and Oxidation Resistance" won the first prize of National Technological Invention in 2004. The following items in daily life also belong to "composite materials":
A. Automobile tires B. Glass
C. Strengthening D. Application of compound fertilizer in agriculture
6. Chemistry is everywhere in life. The use of the following substances has nothing to do with their chemical properties:
A. Use baking soda to remove the acid produced in the process of flour fermentation.
B. hydrogen is used to fill the probe balloon.
C. quicklime is used as a desiccant.
D. Rare gas is used as shielding gas for metal welding.
7. In the experiment of CO2 production in the laboratory, the following methods are feasible:
A. Pick up the massive limestone solid with tweezers. B. Put your nose to the bottle mouth to smell the acid.
C, reacting dilute sulfuric acid with massive limestone to prepare CO2 d, and pouring the remaining acid back into the original bottle.
8. For people trapped in the fire area, the following practices are not appropriate:
A. When the smoke is heavy, cover your nose and mouth with a wet towel. B. Squat or crawl in a smoky place.
C. Once the fire is discovered, open all doors and windows immediately. Call the police and get help.
9. The chemicals contained in the automobile airbag can generate the most abundant gas in the air within 10 millisecond after the collision. The gas is:
A. Oxygen B. Nitrogen C. Carbon dioxide D. Rare gas
10. A classmate explores three unknown metals according to the following steps: (1) They are numbered X, Y and Z respectively; (2) Samples were taken and added into CuSO4 solution respectively, and it was found that red substances appeared on the surfaces of X and Z, while Y did not. (3) Adding particles with the same size of X and Z into dilute sulfuric acid with the same solute mass fraction, it is found that the bubble formation speed on the X surface is obviously faster than that on the Z surface ... Then the metal activities of X, Y and Z from strong to weak are as follows:
A.X>Y>Z B.Z>Y>X C.X>Z>Y D. Z>X>Y
1 1. The material characteristics determine its use and preservation method. Solid NaOH has the following properties: ① white flaky solid ② corrosive ③ easy to absorb water and deliquesce ④ soluble in water, and exothermic after dissolution ⑤ can react with carbon dioxide in the air. The main reasons why it must be sealed in the laboratory are:
A.①② B.①②③ C.②③④ D.③⑤
12. The following mixtures that may be encountered in life can be separated by the steps of "dissolution-filtration-evaporation":
A. Salt (NaCl) and fine sand B. Water and alcohol
C. limestone (CaCO3) and quicklime (Cao) D. sucrose and monosodium glutamate
13. Which of the following reagents is most suitable for removing a small amount of sodium carbonate mixed in sodium chloride solution:
A. sodium hydroxide solution B. sulfuric acid solution C. hydrochloric acid solution D. calcium hydroxide solution.
14. Washing problems in life are mostly related to chemical knowledge. The following statement is incorrect:
A. Kitchen cleaners can emulsify oil stains on tableware.
Gasoline can dissolve oil stains on clothes.
C. vinegar can be used to remove scale from hot water bottles.
D tap water can dissolve the rust on the iron fence.
15. At the CCTV Spring Festival Gala in 2005, Gansu Province greeted the audience with the following couplets: "Gold, silver, copper, iron, chromium, nickel, lead and zinc". For this link, the following statement is true:
A. The colors of these eight metals are the same.
The manufacture of B alloy greatly broadens the application scope and use value of these eight metals.
These eight metals can react with dilute hydrochloric acid to produce hydrogen.
These eight metals all exist in minerals as simple substances.
Second, the choice of indefinite items (***5 small questions, 2 points for each small question, * * 10 points for each small question, and the 1-2 option for each small question meets the meaning of the question. Wrong selection will not give points, and missing selection will give 1 point)
16. There is a heating method in the chemical experiment called "hot water bath" (pictured). In view of this heating method, the following statement is wrong:
A the heating temperature of the reagent in the test tube shall not exceed 100℃
B the reagent in the test tube is heated evenly (compared with direct heating by alcohol lamp)
The bottom of the test tube should not touch the bottom of the beaker.
D replace the water in the beaker with salt water, and the heating temperature of the reagent in the test tube will not be higher than 100℃.
17. On March 29th this year, a tanker accident occurred in Huai 'an section of Beijing-Shanghai Expressway, which caused a large area of liquid chlorine leakage, killing 28 people and poisoning hundreds. It is known that chlorine gas (Cl2) is gaseous at normal temperature and pressure, which is denser than air, soluble in water and easily absorbed by alkaline solution (it will react with alkali to generate salt and water). The following treatment methods for on-site rescue of fire police are reasonable:
(1) Command the crowd to move to higher ground in time.
② Transfer personnel should wear masks treated with alkaline solution.
(3) Spray an aqueous solution containing alkaline substances into the air with a high-pressure water gun.
(4) Move the tank containing residual liquid chlorine to a nearby pond, and add quicklime to the pond.
A.① B.①② C.①②③ D.①②③④
18. In 2004, the Nobel Prize in Chemistry was awarded to aaron ciechanover and other three scientists for their discovery of ubiquitin-regulated protein degradation. The following statement about protein is correct:
A. 1965, China scientists synthesized crystalline bovine insulin for the first time in the world on the basis of studying the structure of protein.
B concentrated nitric acid and heavy metal salts will cause chemical changes in protein and lose its original physiological functions.
C. protein is also called carbohydrate.
D. the main components of animal hair (human hair, etc.). ) and plant fiber (cotton, etc. ) They are all protein, and they smell of burnt feathers after burning.
19. Gallium (Ga) has only one valence in the compound, with a relative atomic mass of 70 and a relative molecular mass of 188. Then the relative molecular weight of gallium phosphate is: (hint: the symbol of phosphate ion is PO4)
A. 165
C.305d d. can't be calculated.
Judging from the picture on the right, the following statement is wrong:
A. The solubility of A.NaCl and NH4Cl increases with the increase of temperature.
B. At 20℃, add 20g of NaCl into 50g of water, and it will be completely dissolved after stirring.
At C. T℃, the solute mass fraction of saturated NH4Cl solution and saturated NaCl solution is equal.
D when the NH4Cl solution at 20℃ is cooled to 0℃, its solute mass fraction will inevitably decrease.
Volume 2 (60 points for non-multiple choice questions * *)
Three. Fill in the blanks (unless otherwise specified, 65438 will score +0, ***20).
2 1. Green plants bathed in the sun are quietly undergoing an important chemical change-"photosynthesis". Please write the chemical equation of this change: among the reactants and products of this reaction, those that belong to the simple substance (fill in the chemical formula) and those that belong to the oxide (fill in the chemical formula); This reaction converts energy into chemical energy in organic matter.
22. Soda soda (Na2CO3) belongs to similar substances (fill in "acid", "alkali" or "salt"). Dropping phenolphthalein test solution into soda water solution, the test solution changes color, indicating that the pH value of soda water solution is 7 (fill in "=", "").
Hou, a scientist in China, created a famous method of alkali production-"combined alkali process".
(1) The chemical equation used in the production process of "combined alkali production" can be simply expressed as: ① NH3+CO2+H2O = NH4CO3.
②NH 4h co 3+NaCl = nah co 3↓+NH4Cl③2 nah co 3 na2co 3+H2O+CO2↓
The basic reaction type not involved in this process is () (2 points)
A. Combination reaction B. Decomposition reaction C. Displacement reaction D. Double decomposition reaction
(2) adding ground salt powder in step (2). The purpose of salt grinding is: (2 points)
(3) cooling the filtrate (mixed solution of NH4Cl and residual NaCl) obtained in step (2), and a large number of NH4Cl crystals are precipitated, but NaCl remains in the solution. What do you think may be the reason why NH4Cl crystallized first?
(2 points, please refer to Figure 20). The obtained ammonium chloride belongs to fertilizer in chemical fertilizer.
Baoying is one of the first batch of "national ecological demonstration counties", which is beautiful and rich, and full of water town charm. How can we continue to handle the relationship between development and environmental protection? Please send two initiatives to the people of the county from the perspectives of protecting water resources and protecting air respectively:
From the perspective of protecting water resources: ①;
② 。
From the perspective of air protection: ①;
② 。
Four. Analysis description (unless otherwise specified, each grid 1 minute, *** 12 minute)
24. In China's energy structure, coal combustion accounts for about 70%.
(1) A chemical interest group argued about whether coal contains sulfur. They designed an experiment as shown on the right to determine. Please write the name of instrument A in the picture:. In order to ignite coal, another glass instrument that needs to be used is:
(2) After consulting the information, they found a passage: "Sulfur dioxide can make KMnO4 solution fade (from purple to colorless), and the reaction equation is: 5SO2+2KMnO4+2H2O = = K2SO4+2MNSO4+2".
But the chemical formula of the last substance in the equation is not clearly printed. According to the context, it is known that the substance is an acid. Please infer its chemical formula from what you have learned: (2 points). The valence of Mn element in MnSO4 produced after the reaction is (2 points).
(3) Salt is often composed of ions. For example, KMnO4 is composed of K and MnO4, and K2SO4 is composed of K and SO4. The color of a salt crystal or solution is usually determined by the ions that make it up.
According to the data consulted in (2), please speculate that the purplish red color of KMnO4 solution may be expressed by ions (fill in the ion symbol, 2 points), for the following reasons.
.
25. If H atom is represented by ""and Cl atom is represented by "",the reacted substance in the container in the right figure belongs to (fill in "pure substance" or "mixture"). The chemical equation of this reaction is shown in the figure:
(2 points).
V. Comprehensive inquiry (unless otherwise specified, 65438 +0 points for each space, ***28 points)
26. "Pearl powder" processed from pearls (mainly CaCO3) is a precious Chinese herbal medicine and health care product. However, in recent years, some counterfeit "pearl powder" has appeared on the market, and it is difficult to tell the truth from the falsehood only by naked eyes. In order to provide consumers with identification methods, it is necessary to find out the physical and chemical differences between true and false "pearl powder". The Industrial and Commercial Bureau provides the true and false "Pearl Powder" samples, please explore: (As long as you write the conjecture and plan, you don't need to tell the specific results of the implementation of the plan)
Conjecture 1: The smell of true and false "pearl powder" may be different.
Scheme 1: Take samples and smell them separately to distinguish whether there is any difference in smell.
Guess 2:.
Option 2:.
Guess three:.
Option 3:.
27. The reaction equation of "making oxygen from hydrogen peroxide and manganese dioxide" is: after doing this experiment, a classmate started the following thinking and exploration:
Does the dosage of (1) catalyst MnO2 _ 2 affect the reaction rate?
He did a series of experiments: using 30 ml 10% H2O 2 solution at a time, using different amounts of MnO2 _ 2 powder as catalyst, and measuring the time taken to collect 500 ml of oxygen at a time. The results are as follows: (Other experimental conditions are the same).
Experimental sequence 1 2 3 4 5 6 7 8 9 10
The dosage (g) of MnO2 powder is 0.1.20.30.40.50.60.70.80.91.0.
Time taken (seconds) 1787543222
Please analyze the data in the table and answer: does the amount of MnO2 affect the reaction rate? If so, how is it affected?
A: Yes. (2 points)
(2) 2) Does the solute mass fraction of H2O2 solution affect the reaction rate?
He did another set of experiments: he took 5ml of 30% H2O2 solution at a time, and then diluted it into solutions with different solute mass fractions for experiments. The recorded data are as follows: (All experiments were carried out at room temperature of 20℃, and other experimental conditions were the same)
Experimental sequence 1 2 3 4 5 6 7 8
The mass fraction of H2O2 solution solute is1%3% 5%10%15% 20% 25% 30%.
Amount of manganese dioxide powder (g) 0.20.20.20.20.20.20.20.20.20.20.2
Time taken to collect 540ml gas (seconds) 660 220 205 80 25 9 4 3
Temperature of liquid after reaction (℃) 24 34 39 56 65 67 69 70
Please analyze the data in the table and answer: Does the solute mass fraction of H2O2 solution affect the reaction rate? If so, how is it affected?
A: Yes.
It can also be seen from the data in the table that the reaction is a reaction (fill in "exothermic" or "endothermic").
(3) What other factors may affect the reaction rate?
Please tell me a guess of yours.
28. Jiangsu Baosheng Group, located in Baoying, Yangzhou, is a large state-owned enterprise mainly producing cable products. In the process of cable production, a certain amount of copper-containing waste (such as broken cable) will inevitably be produced. After learning about this situation, four students from a chemistry interest group put forward their own views on "recovering copper from copper-containing waste".
According to the knowledge learned, classmate A put forward a set of recycling scheme:
After consulting the data, student B learned that copper can react with dilute sulfuric acid in solution under the condition of air heating (the equation is 2Cu+2h2so 4+O2 2cus 4+2H2O), so he put forward another scheme:
In the three steps of (1) A scheme, the chemical reaction equations related to copper or copper compounds are respectively:
① ; ② ;
③ 。
(2) Comparing the different parts of the two schemes from the perspective of environmental protection, you think the scheme (fill in "A" or "B") is more reasonable. The reason is:
(3) C thinks that the step of "adding iron filings" in both schemes should add a little excessive iron filings. Why do you think C said that? (2 points)
Ding also raised a question: "If there is too much iron, the remaining iron will be mixed with red powder. What should I do? " . Please put forward your ideas.
(4) Finally, the teacher affirmed the students' positive thinking, but at the same time pointed out: after the light green filtrate obtained in the last step of the scheme is crystallized, an industrial product commonly known as "green alum" will be obtained, which can increase economic benefits. Please write down two possible ways of crystallization of "green vitriol": (With the increase of temperature, the solubility of "green vitriol" increases). If the filtrate is directly discharged, it will not only cause waste, but also.
(5) If the mass fraction of dilute sulfuric acid solute used in the above scheme is 36.8%, it is necessary to prepare this dilute sulfuric acid G according to1000 mL of 98% concentrated sulfuric acid (density: 1.84g/mL), and water mL (density: 1.0g/mL) is required. How to dilute concentrated sulfuric acid in laboratory? (2 points)
(6) According to the equation (2Cu+2H2SO4+O2 2CuSO4+2H2O) discovered by student B, if 98% concentrated sulfuric acid (density: 1.84g/mL) is diluted and all of them participate in the reaction (assuming that sulfuric acid does not react with impurities such as damaged cable sheath), how much pure copper can be contained in the waste that can be treated? Please write down the calculation process, and the result is accurate to 0.1g. 3 points)
Graduated from Yangzhou junior high school in 2005 and took the entrance examination.
Reference answers and grading standards of chemistry (experimental area of curriculum reform)
Marking description
1. All technical and chemical terms (symbols, chemical formulas, etc. ) are not correct.
2. If the chemical equation is not balanced, do not score.
3. Text expression can be scored by answering key words.
4. Other reasonable statements and solutions in the answer can be scored.
The first volume (multiple choice questions ***40 points)
(2 points for each small question, 40 points for * * *. 1- 15 small questions, each question has only one correct answer; 16-20 small questions, each question has 1 ~ 2 options that meet the meaning of the question, and the missing choice is given to 1 point, and the wrong choice and multiple choices are not given points. )
The title is 1 23455 6789 10.
Answer B C D C A B A C B C b c b c b c
The title is11213141516171819 20.
Answer D A C D B D A, B A B, d.
Volume 2 (60 points for non-multiple choice questions * *)
3. Fill in the blanks (unless otherwise specified, 65438 will get +0 points for each blank, and ***20 points).
21.6co2+6H2O c6h12O3+6o2 (arrows can be written as equals signs, light can be written as light and sunlight, and chlorophyll can be written as chloroplasts). Do not write conditions, do not score); Oxygen, carbon dioxide, H2O；; Light (energy) or the sun (energy).
22. salt, red, alkali, >.
( 1)C .
(2) Increase the contact area between salt and water, accelerate the dissolution of salt, and then speed up the reaction. If you answer one of the key words such as "increasing contact surface", "accelerating dissolution", "accelerating reaction" and "making the reaction fully proceed", you will get a score. )
(3) 3) The solubility of NH4Cl is greatly affected by temperature, while the solubility of NaCl is not affected by temperature (score in one sentence).
Nitrogen (fertilizer).
23. Protect water resources: Prohibit phosphorus-containing washing powder; Domestic sewage and industrial sewage are discharged up to standard; Rational use of pesticides and fertilizers in agriculture.
Protect the air: burning straw is prohibited in farmland; Cars are equipped with tail gas purification devices; Do not burn garbage at will; Encourage the use of pollution-free green energy such as solar energy.
This question is an open-ended question, and all the answers that meet the theme and are practical can be scored.
Four. Analysis description (unless otherwise specified, each grid 1 minute, *** 12 minute)
24.( 1) Crucible pliers. spirit lamp
(2) sulfuric acid.
(3) MnO 4-, there is K+ in the colorless solution after the reaction, indicating that K+ is colorless, so MnO 4 is used to represent purple-(all reasonable answers can be scored).
25. Pure stuff. H2+Cl2 ignites 2HCl.
V. Comprehensive inquiry (unless otherwise specified, 65438 +0 points for each space, ***28 points)
26. Guess: The solubility of true and false "pearl powder" in water may be different;
Scheme: Sampling, adding appropriate amount of water and stirring respectively, and observing whether their solubility is different.
Guess: the reaction between true and false "pearl powder" and acid may be different;
Scheme: Sampling, adding appropriate amount of dilute hydrochloric acid respectively, and observing whether there is any difference.
Guess: the true and false "pearl powder" may have different phenomena after burning;
Scheme: sampling, burning on the flame of alcohol lamp for a while, and observing the color change.
The purpose of this topic is to examine students' basic scientific inquiry ability, that is, the basic ideas and methods that should be adopted when exploring the common unknowns in life. Therefore, reasonable and practical guesses and schemes can be scored.
27.2 H2O 2 MnO 2·2H2O+O2↑
(1) has an impact. In a certain range, the greater the amount of MnO2, the faster the reaction ("influential" is not counted. The keywords "within a certain range" and "the greater the amount of MnO2, the faster the reaction" each account for 1 minute. )。
(2) it has an impact. The greater the solute mass fraction of H2O2 solution, the faster the reaction (regardless of "influence"). Answer the following question: "The greater the solute mass fraction of H2O2 solution, the faster the reaction." In order to score). calorific
(MnO _ 2 particle size, ambient temperature, air pressure and oscillation can give a reasonable answer.
28.( 1) ① 2cu+O2 heating ② CuO ② CuO+H2SO4 = = CuSO4+H2O; ③ Iron+copper sulfate = = ferrous sulfate+copper.
(The "heating" condition of Equation ② is not required)
(2) B. The first step of "combustion" in Scheme A will produce gas, dust and smoke that pollute the air. (Keywords: "air pollution")
(3) "Ensure that CuSO4 is used up" or "completely replace Cu", and other similar expressions can be scored.
Washing and drying the obtained copper powder after pickling; Or adding an appropriate amount of acid before filtration to remove the remaining iron powder. (Keywords: "adding acid")
(4) evaporative cooling. Water pollution or environmental pollution.
(5)4900 ,3060 。 Add concentrated sulfuric acid into water along the glass rod (key word "concentrated sulfuric acid into water", the correct order is fraction).
(6) Solution: Let the mass of pure copper in the waste that can be treated be X. ..
2Cu + 2H2SO4 + O2 2CuSO4 + 2H2O
2×64 2×98
X 1000 ml×1.84 g/ml× 98%
(Format and process: 2 points)
2×64 2×98
X 1000 ml×1.84 g/ml× 98%
X = 1 177.6g ( 1)
A: The waste that can be treated contains 1 177.6 grams of pure copper.
In 2005, the chemistry examination questions in the senior high school entrance examination in Xining city.
Possible relative atomic mass: ca-40h-1c-12cl-35.5o-16.
A, multiple-choice questions (this question has 14 small questions, each with 2 points and ***28 points. Only one option in each question meets the meaning of the question, please fill in the letter of the correct option in the brackets on the right)
1. The following changes are physical changes ().
A. spontaneous combustion of white phosphorus B. oxygen production by air liquefaction C. iron rust D. alcohol combustion
2. The following substances are pure ()
A. sucrose solution B. coal C. iodine D. distilled water
3. Add the following substances into enough water respectively, and form a solution () after fully stirring.
A. Salt B. Limestone C. Flour D. Vegetable oil
4. Among the following substances, the one with oxygen molecules is ().
A. carbon dioxide b air c ethanol d potassium permanganate
5. The most closely related to the chemical properties of elements is ().
A. Number of electron layers outside the nucleus B. Number of neutrons inside the nucleus C. Number of outermost electrons D. Relative atomic mass
6. In order to realize sustainable development, Xining has implemented measures to improve the ecological environment in recent years, such as "Blue Sky Project", "Quiet Project" and "Clear Water Project". In order to protect water resources, the following practices are wrong ()
A. rational use of pesticides and fertilizers in agriculture B. industrial wastewater is discharged after treatment.
C. Arbitrary discharge of domestic sewage D. Application of new processes and technologies to reduce the generation of pollutants.
7. The following substances have uses, mainly using chemical properties is ()
A. Artificial rainfall with ice B. Using liquefied natural gas as automobile fuel.
C. titanium alloy artificial bone D. cutting glass with diamond.
8. After learning chemistry knowledge, you can use household necessities for chemistry learning and inquiry activities. What you can't do with household necessities in the following experiment is ().
A. Can eggshells be dissolved in acid B. Explore under what conditions iron products will rust.
C, identify salt and soda d, and check whether the tap water contains chloride ions.
9. Calcium hydroxide solution by introducing or adding the following substances, can't significantly reduce the pH value of the solution is ().
A. sulfuric acid B. copper chloride C. barium chloride D. carbon dioxide
10. There are many "equals" or "equals" in chemical knowledge. The following statement is incorrect ().
A. The total mass of substances participating in a chemical reaction is equal to the total mass of substances generated after the reaction.
B. The total positive valence of elements in a compound is equal to the total negative valence.
C, the quality of solute before and after solution dilution is equal.
The number of protons in the nucleus is equal to the number of neutrons.
1 1. In the following groups of gases, () is both flammable and reducing.
A.H2, carbon monoxide, carbon dioxide, H2, carbon dioxide, H2, methane
12. The following chemical equation conforms to the changing fact ().
A. iron wire burns 4fe+3o2o2fe2o3 in oxygen.
B. Take medicine to treat hyperacidity 2Al(OH)3+3H2SO4=Al2(SO4)3+6H2O.
C. Soon after painting the wall, the lime slurry hardened. Calcium hydroxide+carbon dioxide = calcium carbonate ↓+H2O.
D. The main reaction in ironmaking blast furnace is 2fe2o3+3c4fe+3co2 =
13. The following experimental operation is correct ().
A. dilute the concentrated sulfuric acid with a measuring cylinder; b. put the remaining drugs back to the original reagent bottle.
C. ignite another alcohol lamp with a burning alcohol lamp D. check the air tightness of the equipment before making gas.
14. The following substances can only be distinguished by colorless phenolphthalein and mutual reaction ().
A. Sodium hydroxide, hydrochloric acid and sulfuric acid
C sodium nitrite, hydrochloric acid, sodium chloride, sodium hydroxide, barium hydroxide and sodium chloride
2. Fill in the blanks (this question includes 4 small questions, 2 points for chemical equation, and the rest 1 point, * * 14 point. )
15. expressed by chemical symbols: 2 hydrogen atoms _ _ _ _ _ _; 1 nitrogen molecule _ _ _ _ _; 2 magnesium ion _ _ _ _ _ _ _ _; Oxygen in water is bivalent _ _ _ _ _ _ _.
16. At the beginning of this year, bird flu occurred in Bird Island area of Qinghai Lake, causing some migratory birds such as spotted geese and fish gulls to get sick and die. In order to prevent the spread of the epidemic, infected birds are often buried deep and removed with lime powder. The main component of quicklime is (write chemical formula) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. Fractional equal temperature
17. There are four kinds of compounds: A, B, C and D. It is known that these four kinds of compounds are all composed of three elements of Na, H, S, C and O. Among them, A+E-P+H-2O-B+D-C+H-2O+CO2 ↑. According to the information of substance change and composition provided above, please write down the chemical formulas of these four compounds: A. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
The solubility curves of 18.A and B are shown on the right. Please refer to the chart on the right.
Answer the question:
① solubility of a at t 1℃ _ _ _ _ _ _ _ solubility of b (fill in ">")
Or "