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I. Multiple Choice Questions (***5 questions, 3 points each, 15 points)
1. The reciprocal of the is equal to ( )
A. -2 B. 2 C. D. Show Analysis 2. The following equations are correctly operated ( )
A. a2+a3=a5 B. a2?a3=a5 C. (ab2)3=ab6 D. a10÷a2=a5
☆☆☆☆☆ shows the analysis 3. The diagram shows the view of a hollow cylinder in the specified direction, and the correct one is ( )
A. B. C. D.
★★★★★☆☆shows the explanation 4. The following four figures are both axisymmetric and centrosymmetric ( )
A. Equilateral triangle B. Parallelogram C. Isosceles trapezoid D. Square
Show Analysis 5. The daily maximum temperatures for five consecutive days in May in a certain city are 23, 20, 20, 21, 26 (unit: ℃), and the median and the multitude of this set of data are ( )
A. 22 ℃, 26 ℃ B. 22 ℃, 20 ℃ C. 21 ℃, 26 ℃ D. 21 ℃, 20 ℃
Show analysis
Two, fill in the blanks (***8 questions, 3 points each, out of 24 points)
6. 4 of the arithmetic square root of ． ★★★★★ shows the analysis 7. Factoring: mx-my= ． ☆☆☆☆☆ shows the analysis 8. The range of values of the independent variable x in the function is ． ★★★★★ show analysis 9. In an opaque cloth bag there are 2 white balls and 3 yellow balls, which are identical except for their different colors. If a ball is randomly drawn from the bag, the probability of drawing a yellow ball is ． Showing the analysis of 10. City Bureau of Statistics released the "Meizhou City in 2010, the sixth national population census of the main data bulletin" shows that the city on November 1, 2010, the zero hour census registration of the resident population of about 4,200,000 people, this figure is expressed in scientific notation for the people. Show analysis 11. As shown in the figure, in Rt△ABC, ∠B=90°. ED is the perpendicular bisector of AC, intersecting AC at point D and BC at point E. It is known that ∠BAE=30°, then the degree of ∠C is °. Show analysis 12. As shown in the figure, in the two concentric circles centered on O, the chord AB of the larger circle is tangent to the smaller circle at point C. If the length of AB is 8 cm, the area of the shaded part of the figure is cm2. Show analysis 13. The number of diagonal lines of a convex n-side shape is recorded as an (n ≥ 4), for example, a4 = 2, then: ① a5 = ; ② a6 - a5 = ; ③ an +1 - an = ③ ③ a6 - a5 - a5 = ③ an +1 - an = ③ an +1 - an = ③ an +1 - an = ③ an + 1 - an = . (n ≥ 4, expressed in terms of the algebraic formula contained in n) Show analysis
Three, answer the question (***10 questions, full of 81 points)
14. Calculation: . Show analysis 15. Simplify: (a+b)2-(a-b)2+a(1-4b) Show analysis 16. After counting the scores of a certain mock examination of the nine (first) classes of Hedong Middle School, Mr. Wang plotted a histogram of frequency distribution. According to the graph, answer the following questions: (Fill in the results directly)
(1) There are three students in the class;
(2) The frequency of the group 89.5 - 99.5 is , and the frequency is .
(3) Estimate the average score of the class on this math practice test as ． Show analysis 17. As shown in the figure, in the plane right-angle coordinate system, point A (-4, 4), point B (-4, 0), the △ ABO around the origin O clockwise rotation 135 ° to get △ A1B1O. answer the following questions: (directly write the results)
(1) ∠AOB = °;
(2) vertex A from the beginning of the A1 after the path length of ;
(3) The coordinates of point B1 are . Show analysis 18. As shown in the figure, point P is on the CD side of parallelogram ABCD, connect BP and extend the extension line with AD to intersect at point Q.
(1) Prove that: △DQP ∽△CBP;
(2) When △DQP ì △CBP and AB = 8, find the length of DP. Show analysis 19. As shown in the figure, the graph of the inverse proportional function and the graph of the primary function y2 = -x + b intersect at the points A and B, where A (1, 2).
(1) find the value of m, b;
(2) find the coordinates of point B, and write the range of values of x when y2>y1. Show analysis 20. In order to encourage urban residents to save water, a city provides water charges are as follows: each household monthly water consumption does not exceed 20 degrees (1 degree = 1 meter 3), the water bill for a yuan / degree; more than 20 degrees, not more than part of the a yuan / degree, more than part of the b yuan / degree. Known as a user of four water 15 degrees, pay water bills 22.5 yuan, 30 degrees of water in May, pay water bills 50 yuan.
(1) find the values of a, b;
(2) if it is estimated that the user's water bill for the month of June is not less than 60 yuan, but not more than 90 yuan, find the range of values of the user's water consumption x in June. Show analysis 21. As shown in the figure, isosceles trapezoid ABCD, AB∥CD, AD=BC. After folding △ACD along the diagonal AC, the point D coincides with the midpoint M of the side AB.
(1) Is the point C on the circle with diameter AB? Explain;
(2) Find the area of this trapezoid when AB=4. Show analysis 22. As shown in the figure, the parabola y=x2-4x+3 is known to intersect the x-axis at two points A and B, and its vertex is C.
(1) Is the point M (m, -2) on this parabola for any real number m? State the reason;
(2) Prove that △ABC is an isosceles right triangle;
(3) Knowing that the point D is on the x-axis, does the point P exist on the parabola such that the quadrilateral with B, C, D, and P as vertices is a parallelogram? If there is, find the coordinates of point P; if not, please explain the reason.VIP show analysis 23. As shown in Figure 1, it is known that the length of the line segment AB is 2a, the point P is a moving point on AB (P does not coincide with A, B), respectively, AP, PB as the side to the same side of the line segment AB as a positive △ APC and positive △ PBD.
(1) When the sum of the areas of △ APC and △ PBD takes a minimum value AP= ; (write the result directly)
(2) Connect AD and BC, intersect at point Q. Set ∠AQC=α, then does the magnitude of α change with the moving surface of point P? Please explain the reason;
(3) As in Figure 2, if point P is fixed, rotate △PBD around point P in clockwise direction (the rotation angle is less than 180°), at this time, does the size of α change? (only need to write your guess directly, do not have to prove)
2010 Meizhou City, Guangdong Province, Guangdong Province, Physics test paper
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One, multiple-choice questions (***12 questions, 3 points per question, 36 points)
1. Some of the energy in the natural world once consumed it is very difficult to regenerate, so we have to We need to conserve energy. In the following energy sources, belonging to non-renewable energy is ( )
A. wind energy B. hydroelectric energy C. solar energy D. petroleum to show the analysis of the 2. LED lights is a new type of energy-efficient light source, which is the core component of the light-emitting diode. The diode is made of which of the following materials ( ）
A．Ceramic materials B．Metal materials C．Semiconductor materials D．Superconducting materials
Show the analysis of the 3．On the molecules, you think that the following statement is incorrect ( ）
A．All the objects are made of molecules
B．Molecules will never stop doing the irregular movement
C． C．There are interaction forces between molecules
D．Some molecules have only gravitational forces, and some have only repulsive forces
Showing the analysis of the 4．Since March this year, the H1N1 influenza virus that originated in Mexico has been spreading rapidly around the world. Xuwen middle school school canteen in order to ensure the health of teachers and students, adhere to the teachers and students used tableware for high temperature steam sterilization. From the tableware into the cold water until heated to boiling water in the process, the following relevant physical quantities on the tableware certainly did not change ( )
A. Temperature B. Volume C. Mass D. Density
show the analysis of the 5. in the use of household electrical appliances, the following statements are correct ( )
A. washing machine using three-hole sockets mainly to prevent lightning
B. refrigerator close to the wall, the following statement is correct ( )
A. the use of three-hole outlets in order to prevent lightning
B. A. Refrigerators are placed close to the wall to dissipate heat
C. Televisions still consume electricity when they are in standby mode
D. Rice cookers can't be connected to the circuit after the plug has been dipped in water because they are prone to breaks
Showing the analysis of the 6. The correct statements about the sound and the electromagnetic waves are ( )
A. Sound and electromagnetic waves can transmit information and can be transmitted in a vacuum.
B. The installation of double-glazed windows in a house can reduce the impact of noise on the room
C. The "stethoscope" can make the human heart vibration amplitude increases, the loudness increases
D. Only when the owner says the secret word can open the "sound lock", which recognizes the voice
C. The power consumed by Ming's house when he took the picture was 9316 KW?h?
D. The power consumed by Ming's house when he took the picture was 931.6 J?
Showing the analysis of the 8. In the following processes, the gravitational potential energy of an object is converted into kinetic energy ( )
A. The process of a parachutist's uniform descent through the air
B. The rise of a hot air balloon
B. The rise of an aerostat
B. The rise of a hot air balloon
B. The rise of an aerostat
C. the process of cars traveling at a constant speed on the horizontal road
D. the process of free fall of the lead balloon
show the analysis of the 9. With the rapid development of the country's economy, the residents of the standard of living improved significantly, the car is gradually entered into thousands of households, on the car of the application of the knowledge of physics, the following is not correct ( ）
A. The rearview mirror can expand the field of vision, is conducive to avoiding traffic accidents
B. The seat belt to do a wider, is to reduce pressure and ensure safety
C. The car brakes sharply due to the inertia but also skidding for a distance
D. The pattern on the car tires is designed to reduce the friction between the ground
show the analysis of the 10. Xiaoyu students by rope Xiaoyu pulls a stone on the horizontal desktop to do uniform circular motion, assuming that it is subject to the disappearance of all the forces, the stone will ( )
A. do uniform linear motion B. continue to do uniform circular motion
C. fall to the ground D. immediately stop moving
show the analysis of the 11. as shown in the figure of the circuit, the power supply voltage is constant, when the key K is closed ( )
A. the voltage is constant, when the key K closed (
D.). p>
A. the voltage becomes smaller, the current becomes smaller, and the lamp becomes dim
B. the voltage becomes larger, the current becomes larger, and the lamp becomes brighter
C. the voltage remains the same, the current remains the same, and the brightness of the lamp remains unchanged
D. the voltage remains the same, the current becomes smaller, and the lamp becomes dimmer
VIP Show Analysis 12. The mass of 100g of the object into the 100mL of alcohol in the cylinder (known ρ alcohol = 0.8 × 103kg/m3), the object is stationary, the alcohol level rises to the 200mL mark, the object in the cylinder is ( )
A. the object is sunk in the bottom of the cylinder B. the object floats in the alcohol level
C. the object is suspended in the alcohol D. There are not enough conditions to determine
VIP Show Analysis
Two, fill in the blanks (***6 questions, 3 points each, 18 points)
13. units and unit conversion: the mass of a blue whale in the ocean is about 120t = kg; the mass of a ninth-grade boy is about 6 × 104; the density of the marble used for the floor of our classroom is about 2.7 × 103. The density of the marble used for the floor in our classroom is about 2.7 × 103 . Show analysis 14. Xiaoming made an electromagnet by wrapping a wire around a nail and connecting it to the circuit shown in the figure. Close the switch S, the left end of the small magnetic needle at rest should be pole, when the slide P of the sliding varistor to the left, the magnetism of the electromagnet will ． Show analysis 15. As shown in Figure A is a modern city many intersections installed surveillance cameras, which can be taken driving violations or traffic accidents when the scene photographs. The lens of the camera is equivalent to a lens, its working principle and (fill in "camera", "projector" or "magnifying glass") similar. As shown in Figure B and C is a car through the intersection with a bicycle collision was successively photographed two photos, the figure can be seen by the car is gradually (fill in "near" or "away") camera.
Show the analysis of 16. As shown in the figure for the measurement of the mechanical efficiency of the pulley block experimental setup, the total weight of the hook code 6N.
(1) the experiment to be vertically upward pulling the spring loaded dynamometer, from the figure can be seen that the size of the pull force N, if the hook code rose to a height of 8cm, the spring loaded dynamometer upward cm, the pulley block of the mechanical efficiency of the ．
(2) If only increase the number of hook yards, the pulley block mechanical efficiency will ． (Optional: "increase", "decrease" or "unchanged") VIP show analysis 17. China's famous wine Wuliangye known as "three cups under the belly body cool, a drop of lip full of fragrance A drop of lip full of flavor" praise, once won the World Expo two gold medals. There is a boutique Wuliangye, it is marked on the box capacity of 500mL, (ρ wine = 0.9 × 103kg / m3), it is loaded with the mass of wine kg, will be poured out half of the wine after the remaining density of wine kg / m3; if this bottle is filled with water, then the total mass of the bottle is full of wine more than kg. Show the analysis of the 18. shown in the figure is the principle of the electric water heater is a simple schematic diagram, the water heater can be in the heating or insulation by the switch S When the switch S is closed, the water heater is heated or kept warm. When the switch S is closed, the water heater is in the state. In the water heater storage bucket filled with water to the highest water level, the mass of water in the bucket is 10kg, the water from 28 ℃ heated to 98 ℃ when the need to absorb heat J, equivalent to the complete combustion of kg of coke release of heat. [The specific heat capacity of water is known to be 4.2 × 103J / (kg?℃), the calorific value of coke is 3.0 × 107J / kg].VIP show analysis
Three, answer the question (***9 small questions, full of 46 points)
19. As shown in the figure, the metal ball submerged in the bottom of a container filled with water, which *** by the action of the three forces, try to draw its force in the figure. The force on the sphere is shown in the diagram. Show analysis 20. train in the back of the carriage has two toilets, only when the door of the two toilets are closed (each door pin is equivalent to a switch), the indicator in the carriage of the indicator light will glow, the indicator will show "toilet someone" words to remind travelers of the two toilets are inside someone, please put the components in the picture Please connect the components in the diagram with the symbols to form a circuit diagram that meets the above design requirements. Show analysis 21. In the investigation of "solid melting temperature change rule" experiment, an experimental group of students according to the measured data plotted as shown in the figure.
(1) by the image can be seen that the melting point of the substance is ℃, at the end of the 2min the substance in (fill in the "solid", "liquid" or "solid-liquid **** survival state). ").
(2) The melting process of the substance is characterized by continuous heat absorption, temperature, internal energy increases.
(3) Comparing the AB and CD segments in the figure, it can be seen that if the same temperature is raised, the segment absorbs more heat. Show analysis 22. As shown in the figure is "to investigate the law of plane mirror imaging" experiment; vertical transparent glass plate below the ruler, the ruler and the glass plate perpendicular; two identical candles A, B vertical and glass plate on both sides of the ruler, to A candle for the imaging object.
(1) for easy observation, the experiment is best in (choose "brighter" or "darker") environment; in addition, the use of transparent glass instead of a plane mirror, although the image is not as clear as a plane mirror, but can be observed in the A candle like the At the same time, can also observe , cleverly solve the problem of determining the location and size of the image, if there is a thicker glass plate and a thinner glass plate, the experiment should be selected glass plate.
(2) light the A candle, carefully move the B candle, until the image of the A candle coincides with the A candle, then found that the size of the image and the object; further observation of the A, B two candles in the ruler found that the image and the object to the distance of the glass plate.
(3) remove the candle B, put a light screen in place, the light screen (fill in "can" or "can not") show the image of the candle, that the object in the plane mirror into the (fill in "real" or "virtual"). "or" imaginary "）like in the plane mirror.
(4) in order to confirm the above imaging characteristics are reliable, you think to take which of the following operations ( )
A, keep the position of the two candles A, B unchanged, many times change the position of the glass plate for observation;
B, keep the position of the glass plate unchanged, many times change the position of the A candles, and carry out the same operation with the above (2).VIP show analysis 23. Xiao Zhou students to do to explore "the relationship between current and resistance" experiment, he designed to connect the physical connection as shown in the figure.
(1) Please draw the corresponding circuit diagram according to the physical connection diagram in the question.
(2) In the experiment, Zhou students first 5 Ω of resistance R into the circuit, the circuit is connected correctly, the sliding varistor resistance adjusted to the maximum, close the switch S directly read out the ammeter, and record the data in the table. Then replace the 5Ω resistor with a 10Ω and 20Ω resistor respectively, and repeat the above operation. His mistake during the experiment was that he did not keep the resistance R unchanged.
(3) Zhou found the error and re-experiment, the data shown in the table below. According to the experimental data in the table to conclude that: ． 2010 Guangdong Province, Meizhou City, chemistry examination paper
Collection of test papers test paper analysis show answers to download the paper
A, multiple choice questions (this question includes 15 questions, 2 points per question, ***30 points. (Each sub-topic only one option meets the meaning of the question)
1. This year's National "Two Sessions" representatives of the members of the use of "stone paper", calcium carbonate as the main material, made after a special process. Calcium carbonate belongs to ( )
A. oxide B. acid C. alkali D. salt show analysis 2. daily life of the following changes, one of the three categories with the rest of the different ( )
A. melting snow and ice B. grape wine C. moldy food D. fireworks exploded
show analysis 3. our food, clothing and shelter are inseparable from a variety of materials, the following materials are The following materials are organic synthetic materials ( )
A．Cotton B．Plastic C．Cement D．Steel
Show analysis4．The idiom of "drinking hemlock to quench thirst" refers to the wine with arsenic. Arsenic is an oxide of arsenic (As), which is highly toxic. The valence of arsenic in arsenic is +3, then the chemical formula of arsenic ( )
A. As2O B. AsO C. As2O3 D. AsO2
Show the analysis of the 5. "Gold, silver, copper, iron and tin" is commonly known as hardware, in the five kinds of metal, there is a kind of metal and the other four kinds of metal salts can react, this metal is (). Reaction, this metal is ( )
A. Gold B. Copper C. Iron D. Tin
show the analysis of the 6. When the car was hit by a certain force, airbags in the material will be rapidly decomposed, generating a maximum content of air gas, so that the airbag popped out and rapidly expand to protect the safety of people in the car. The gas is ( )
A. O2 B. N2 C. CO2 D. He
Show analysis 7. a student had diarrhea symptoms, the doctor recommended not to eat foods rich in fat and protein, then he should choose the breakfast is ( )
A. eggs and milk B. steamed bread and rice
C. doughnuts and soymilk D. fried chicken pieces and yogurt
Show analysis 8. The following substances can be smelled after mixing and grinding with slaked lime powder ( ）
A. K2CO3 B. CO(NH2)2 C. NH4Cl D. Ca3(PO4)2
Show analysis 9. The following are the correct ways to deal with the accidents ( ）
A. When the household appliances are on fire, put out the fire with water immediately.
B. When a fire breaks out indoors, immediately open windows and doors to ventilate the room
C. When a frying pan catches fire while stir-frying, immediately pour water on the fire
D. When fighting a forest fire, set up a quarantine zone
Show explanation 10. The following practices do not cause food to be hazardous to human health
A. Baking powder is used to bake pastry with baking soda
B. Baking powder is used to make baked goods
B. Baking soda is used as a baking powder
C.
B. Sulfur fumigation of white fungus, vermicelli and other food products
C. Formaldehyde solution as a preservative for edible aquatic products
D. Industrial salt containing sodium nitrite for pickling food
Show analysis 11. The following substances in the air after being left for a certain period of time in an open mouth, due to the occurrence of a chemical change to increase the mass of the ( )
A. Concentrated hydrochloric acid B. Concentrated hydroxyacid C. Concentrated hydroxyacid D. Concentrated hydroxyacetic acid E. Concentrated hydroxyacid F. A. Concentrated hydrochloric acid B. Concentrated sulfuric acid C. Sodium chloride D. Quicklime
Show analysis 12. deflated ping-pong ball into the hot water can bulge, because the gas inside the ball ( )
A. intermolecular spacing increases B. molecular volume increases
C. number of molecules increases D. molecular mass increases
Show analysis 13. the following experimental operations A. Extinguish the alcohol lamp B. Read the liquid
C. Weigh the NaOH solid D. Determine the pH of the solution
Show explanation 14. The following is a wrong understanding of "Chemistry and Life". A. Use gasoline to remove oil stains from clothes
B. Excessive intake of trace elements is not good for health
C. Conserve water by using more than one type of water
D. Separate recycling garbage and burn it in the open air
Show analysis 15. The following substances are correctly identified by the following methods
A. Identify by looking at the color
B. Identify by looking at the color
C. Identify by looking at the color
C. Identify by looking at the color
C. Identify by looking at the color
C. A. the method of color observation to identify oxygen and nitrogen
B. the method of filtration to identify the distilled water and sucrose water
C. the use of CaCl2 solution to identify the Na2CO3 solution and Ca (OH) 2 solution
D. the use of clarified lime water to identify the hydrogen and carbon monoxide
show the analysis
II. 6 questions, ***35 points)
16. Life contains science, pay attention to all learning. The following common substances: ① SO2, ② C2H5OH, ③ NaOH, ④ NaCl, ⑤ C, ⑥ CH3COOH. Please select the appropriate substance number to fill in the blanks:
(1) commonly known as caustic soda is ．
(2) It is used in medicine to prepare saline.
(3) One of the air pollutants is ．
(4) It can be used as a dry cell electrode.
(5) The acid contained in vinegar is ．
(6) It can be used as fuel for alcohol lamps. Aluminum is the most abundant metallic element in the earth's crust and is widely used in production and life. The atomic structure of aluminum is shown schematically.
Please answer:
(1) The value of x in the diagram is , the number of protons in the nucleus of the aluminum atom is .
(2) Aluminum has a good resistance to corrosion because (expressed by chemical equation) ． Show analysis 18. "Greenhouse effect" is the Copenhagen Climate Change Conference to study one of the environmental issues, CO2 is currently the highest content of a greenhouse gas in the atmosphere.
(1) Write two uses of CO2 , ．
(2) The following measures are conducive to reducing the concentration of CO2 in the atmosphere is (fill in the serial number).
①encourage travel by bus, advocate a low-carbon life
② vigorously develop thermal power generation
③ energy-saving technologies to reduce the amount of fossil fuels
④ development and utilization of new energy sources such as solar energy, wind energy
(3) In order to reduce the emission of CO2, another way to realize the carbon cycle is to convert CO2 into organic matter, such as CO2 and H2 in the catalyst and heating conditions to produce methane and water. The chemical equation of the reaction is ． Show analysis 19. a natural mineral water label has the following text description: "water quality main components (mg / L): K + 0.62-3.25 Na + 18.7-29.8 Ca2 + 17.8-26.2 Cl- 14.2-30.8 sulfate 41.6-70.2 bicarbonate 184-261 pH 7.3 "
(1) The chemical symbol for the sulfate ion is; the meaning of the number "2" in "Ca2+" is ．
(2) The mineral water is (fill in "acidic", "alkaline" or "neutral").
(3) In our daily life, we can distinguish between soft water and hard water, and we can reduce the hardness of water by the method. The solubility curves of two solid substances X and Y are shown in the figure on the right. Answer the following questions:
(1) The solubility curves of X, Y two substances can be judged by the solubility of the greater influence of temperature is ．
(2) 40 ℃, the solubility of Y is g; 60 ℃, 45 g of X into 50 g of water, fully dissolved, to get the temperature of the aqueous solution of X is (fill in "saturated" or "unsaturated") solution.
(3) from the saturated solution of Y, Y should be extracted by (fill in "cooling crystallization" or "evaporation solvent"). Show analysis 21. A ~ H is a common substance in junior high school chemistry. It is known that A is a black solid monomer, G is a purplish-red solid monomer, B is a reddish-brown powder, F is a black powder, and their transformation relationship is shown in the figure below.
Please answer:
(1) The chemical formula of B is , and the chemical formula of F is .
(2) Among the three substances A, C and E, the reducing ones are , (fill in the chemical formula).
(3) The chemical equation of reaction ① is; write a chemical equation that can realize reaction ③ ．
(4) The basic types of chemical reactions involved in reactions ① to ④ are , and . Show analysis
Three, short answer questions (this question includes 2 sub-questions, *** 21 points)
22. The figure below is a common laboratory experimental setup, please answer the relevant questions:
(1) Device C consists of a conduit, and (fill in the name of the instrument).
(2) laboratory with H2O2 and MnO2 O2 chemical equation for the selection of the device is (fill in the number, the same below); if the use of KClO3 and
MnO2 O2 production, then the selection of the device is ．
(3) The chemical equation for the production of CO2 in the laboratory is ． If HCl and H2O are mixed in the CO2 produced, and NaOH solid is used to remove impurities during purification, do you think that this method (fill in "feasible" or "infeasible"), the reason is ．
(4) laboratory production of H2 should choose the collection device is or ． A chemistry interest group is investigating whether NaOH solution reacts completely with dilute hydrochloric acid. Please participate in their investigation activities and answer the questions.
Experimental investigation:
(1) Program 1: a student according to the method shown in the figure on the right, first add about 2mL NaOH solution to the test tube, and then drop a few drops of phenolphthalein solution, the solution turned red. Then slowly drop in dilute hydrochloric acid, while dropping and oscillating, until the solution just to change color, proving that the NaOH solution and dilute hydrochloric acid just to react completely.
①Please point out the error in the operation on the right.
②Write a chemical equation for the reaction between NaOH solution and dilute hydrochloric acid.
(2) Program 2:
Experimental Steps Experimental Phenomenon Conclusion
Take Take 2mL NaOH solution in a test tube, drop a certain amount of dilute hydrochloric acid, vibrate and then add magnesium strips If the dilute hydrochloric acid is too much
If there is no obvious phenomenon, the NaOH solution and the dilute hydrochloric acid reacted completely
Experimental Reflection:
(3) Program 1, in which a drop of dilute hydrochloric acid was added, write the chemical equation of the reaction between NaOH solution and dilute hydrochloric acid. ) If a small number of bubbles are observed during the process of dropping dilute hydrochloric acid into the solution, the cause of the bubbles may be (write one).
(4) Some students suggested that program two can not prove that NaOH solution and dilute hydrochloric acid happen to be completely reacted, the reason is ．
Expand the application:
(5) Give an example to show the application of neutralization reaction in production and life ． Show analysis
Four, calculation questions (this question includes 2 subtopics, ****14 points)
24. fertilizer to improve crop yields have an important role, NH4NO3 is a high nitrogen content of the fertilizer.
(1) The mass ratio of the elements nitrogen, hydrogen and oxygen in NH4NO3 is ．
(2) The mass fraction of the element nitrogen in NH4NO3 is ．
(3) To ensure that the crop gets 70 g of nitrogen, at least g of NH4NO3 needs to be applied. Show Analysis
Physical Quantities
Number of Experiments Resistance R
(Ω) Current I
(A)
1 5 0.48
2 10 0.24
3 20 0.12
(4) Zhou students found a small bulb, so use this small bulb to replace the 20Ω resistor, continue the experiment. Meter measured as shown in the figure, it is known that the resistance of the small bulb is Ω. Show analysis 24. incandescent light bulbs can be found everywhere in life, if we look carefully we will find that there are a lot of people have studied the physical knowledge. Please students to complete the following questions:
(1) incandescent light bulb normal light, the current through the filament work will be converted into internal energy and light energy.
(2) incandescent light bulbs used for a long time after the brightness than the new dark, is due to the filament heat (fill in the name of the change of state of matter), the resistance becomes larger, the actual power of the bulb (fill in the "bigger", "smaller" or "unchanged") of the cause.
(3) The light from an incandescent bulb travels in all directions, following the laws of light. Show analysis 25. Briefly explain the relationship between the pressure of a fluid and the speed of flow. A model of an airplane wing is shown in the figure. Explain briefly why an airplane gains upward force. Show analysis 26. As shown in the figure, the mass of object A is m = 12 kg, under the action of tension F, object A moves with a speed of 0.1 m/s in the horizontal plane in a uniform linear motion, and the spring dynamometer shows 12 N. Neglect the friction between the pulley and the rope, as well as the gravitational force of the pulley, the spring dynamometer, and the rope, and the rope is long enough. Find:
(1) the size of the friction f between object A and the horizontal plane;
(2) the size of the tension F;
(3) the object A 10s of the process of movement, the work done by the tension F. VIP shows the analysis of the 27. The diagram shows a device for lifting a heavy weight with a flow motor. It is known that the mass of the weight m = 50kg, the supply voltage U = 110V remains unchanged, the resistance of the motor coil R = 4Ω, not counting the friction, when the motor to a certain speed at a constant speed upward to lift the weight, the current in the circuit I = 5A (g = 10N / kg).
Seek:
(1) the power output of the power supply;
(2) the motor coil resistance R heating power;
(3) try from the point of view of energy conversion and conservation, the size of the rate of rise of the weight. VIP show analysis
25. industry with the method of electrolysis of NaCl solution to produce NaOH, Cl2 and H2. H2, the chemical equation of the reaction is: 2NaCl + 2H2O2NaOH + H2↑ + Cl2↑. Now take a certain mass fraction of NaCl solution 214.6g for electrolysis, when the NaCl completely reacted, the generation of 0.4gH2.
(1) When the NaCl completely reacted, the mass of Cl2 generated g, the mass of NaCl to participate in the reaction is g.
(2) When the NaCl completely reacted, the resulting NaOH solution in the mass fraction of solute? (assuming that Cl2 and NaOH are formed) (Assuming that all of the Cl2 and H2 produced escapes)