answer stringclasses 193
values | category stringclasses 1
value | qid stringlengths 8 77 | images images listlengths 1 1 | problem stringlengths 45 1.82k | id int64 56 38.9k |
|---|---|---|---|---|---|
A | (GradeSchool) Science | MMK12-de5fa4c0-793f-4f5f-a884-dcba4ee0e2bf | <image>
As shown in the figure, two spring force gauges $$A$$ and $$B$$ are hooked together, and then the circular rings of the spring force gauges are pulled horizontally to the left and right by hand. When the reading of the left spring force gauge $$A$$ is $$8\,\rm N$$, the reading of the right spring force gauge $$... | 38,773 | |
A | (GradeSchool) Science | MMK12-c15d36a1-9ea9-4529-af26-0e2758b238ac | <image>
A sinusoidal alternating power source is connected with a resistor $R$ and an AC voltmeter as shown in Figure 1. Given $R=10\Omega$, the reading on the AC voltmeter is $10V$. Figure 2 shows the graph of the output voltage $u$ of the alternating power source as a function of time $t$. Which of the following stat... | 38,774 | |
A | (GradeSchool) Science | MMK12-0a6e6401-2bac-446d-98c6-335cadab2a77 | <image>
As shown in the figure, the thickness of the rectangular metal sheet is uniform, with side lengths $l_{ab}=10\:cm$ and $l_{bc}=5\:cm$. When $C$ and $D$ are connected to a circuit with a constant voltage $U$, the current is $2\:A$. If $A$ and $B$ are connected to a circuit with the same constant voltage $U$, the... | 38,775 | |
D | (GradeSchool) Science | MMK12-86322ce5-eadc-46c6-a560-7527a082b4fa | <image>
As shown in the figure, AB is a diameter of a semicircle, AO = OB, and P is a point on the circumference. Three concurrent forces F$_{1}$, F$_{2}$, and F$_{3}$ act at point P. Given that F$_{2}$ = 3 N, their resultant force is ()
A. 4.5 N
B. 6 N
C. 7.5 N
D. 9 N | 38,777 | |
B | (GradeSchool) Science | MMK12-a884f99b-c61e-47b3-aede-2afd51913905 | <image>
As shown in the figure, a smooth inclined plane of height $$h$$, a block of mass $$m$$ is able to move up the inclined plane at a constant speed under the action of a constant force $$F$$ parallel to the inclined plane. If the block is placed at the top of the inclined plane and pulled down with a constant forc... | 38,778 | |
C | (GradeSchool) Science | MMK12-acd9ad4d-82d0-4f29-9aa1-1d306c975885 | <image>
The power unit is installed in each carriage, making it capable of both providing traction and carrying passengers. Such passenger vehicles are called EMUs (Electric Multiple Units). An EMU set consists of several self-powered vehicles (EMUs) and several non-powered vehicles (also called trailers) grouped toget... | 38,779 | |
B | (GradeSchool) Science | MMK12-d6ef6caf-80d3-4a35-ae17-3de9a1f87fa0 | <image>
As shown in the figure, a long wooden board B with a mass of M = 3.0 kg is placed on a smooth horizontal surface. At its right end, there is a small wooden block A with a mass of m = 1.0 kg. Both A and B are given initial velocities of 4.0 m/s in opposite directions, causing A to move to the left and B to move ... | 38,780 | |
A | (GradeSchool) Science | MMK12-e8da1815-a4d7-4f68-b164-2852d5f3e1e6 | <image>
As shown in the figure, there exists a uniform magnetic field perpendicular to the paper with a magnetic induction of $$B$$ in a circular region in the vertical plane, and point $$O$$ is the center of the circular region. A charged particle (neglecting gravity) enters horizontally from point $$A$$ along the $$A... | 38,781 | |
C | (GradeSchool) Science | MMK12-a0ea5f4a-c8fe-4a08-bd45-ecdbc0e958b3 | <image>
A rectangular coil $abcd$, with length $ab=20cm$ and width $bc=10cm$, has $n=200$ turns and a total circuit resistance of $R=50Ω$. The entire plane of the coil is penetrated by a uniform magnetic field perpendicular to the plane of the coil. The magnetic flux density $B$ changes over time as shown in the figure... | 38,783 | |
B | (GradeSchool) Science | MMK12-42b88747-047f-4736-b703-e955a2ef1e06 | <image>
As shown in the figure, a bookshelf is placed on a table 1m high. The height of each of the three layers of the bookshelf is 30cm, and the thickness of the shelves is negligible. Assuming each book has a mass of 1kg and a height of 20cm, and each layer of the bookshelf can vertically hold 10 books, initially al... | 38,784 | |
C | (GradeSchool) Science | MMK12-8f62a2dc-5b0b-4d52-b30c-e8b35a101b47 | <image>
As shown in the figure, the smooth parallel metal rails, with negligible resistance, have a length s = 0.4 m, and the distance between the two rails L = 1 m. The rails are inclined at an angle of 30°, and the upper end ab is connected to a resistor with a resistance R = 2 Ω. A uniform magnetic field with a magn... | 38,785 | |
D | (GradeSchool) Science | MMK12-d0c31c8b-5d51-4272-bcd0-ff055d5c573f | <image>
As shown in Figure A, a crane on a construction site slowly lifts a square workpiece weighing $G$. Four massless and equal-length steel ropes are used, with one end of each rope fixed at the four corners of the square workpiece, and the other ends converging at a point hanging from the hook. The distance from t... | 38,786 | |
B | (GradeSchool) Science | MMK12-61881f05-fa8d-4c35-906f-406e79846813 | <image>
In the 'a-t' graph shown in the figure, which describes the linear motion of an object, the 'rate of change of acceleration' is introduced to describe how quickly the acceleration changes. Which of the following statements is correct?
A. At $$t=1s$$, the 'rate of change of acceleration' is $$1.5m/s^{2}$$
B. Th... | 38,787 | |
A | (GradeSchool) Science | MMK12-60433db9-62b8-49f2-b6f4-bf8287663601 | <image>
As shown in the figure, a charged particle with mass $m$ and charge $q$ is shot vertically upward from point $A$ with an initial velocity $V_{0}$ into a uniform electric field with a horizontal electric field strength $E$. When the particle passes through point $B$, its velocity is $V_{B}=2V_{0}$, and its direc... | 38,788 | |
B | (GradeSchool) Science | MMK12-bcae1682-75fd-4d6f-9309-3c949b19688e | <image>
In the circuits shown in Figure A and B, when 220V AC voltage is applied across points a and b and points e and f respectively, the voltages measured across points c and d and points g and h are both 110V. If 110V AC voltage is applied across points c and d and points g and h respectively, then the voltages acr... | 38,789 | |
B | (GradeSchool) Science | MMK12-b2f48d4b-b817-4f40-bceb-d3c9ec7ee4ac | <image>
Xiao Ming's dining table has two levels. The upper level is a turntable with a radius of $40cm$, and dishes placed on it can rotate around the axis at the center of the turntable. It is known that the coefficient of kinetic friction between the bowl and the surface of the turntable is $0.64$. After Xiao Ming's ... | 38,790 | |
A | (GradeSchool) Science | MMK12-ee2f21c7-2f28-42ed-b132-ca4216156cb2 | <image>
The vast majority of energy consumed on Earth currently comes from nuclear energy released during nuclear fusion inside the Sun. As shown in the figure, the rated power of the solar street lamp is $P$, and the photoelectric conversion efficiency of the solar cell system is $η$. Let $P_{0}$ represent the total p... | 38,792 | |
A | (GradeSchool) Science | MMK12-dc2783f6-fee7-4b70-9240-88a633a07441 | <image>
In the circuit shown in the figure, the power supply voltage remains constant, $$R_{1}=\quantity{10}{\Omega}$$. When the switch $$S$$ is closed and the slider $$P$$ of the variable resistor $$R_{2}$$ is moved to the far right end $$b$$, the ammeter reading is $$\quantity{0.6}{A}$$; when the slider $$P$$ is move... | 38,793 | |
D | (GradeSchool) Science | MMK12-c1257061-ba03-4efb-9ada-563eac11736f | <image>
As shown in the figure, the weight of the spring scales and the fine thread, as well as all friction, are negligible. The weight of the object G is 5N. The readings of spring scales A and B are ( )
A. 5N, 0
B. 0, 5N
C. 10N, 5N
D. 5N, 5N | 38,794 | |
C | (GradeSchool) Science | MMK12-79d18de2-95aa-4002-b706-3a053c8ced4c | <image>
As shown in the figure, a wooden block is at rest on a fixed inclined plane on a horizontal surface. The number of forces acting on the wooden block is ( ).
A. 1
B. 2
C. 3
D. 4 | 38,795 | |
B | (GradeSchool) Science | MMK12-fb9fe13e-ed72-447a-901c-a40c582c4fe6 | <image>
As shown in the figure, a spring with a spring constant of k has a mass m suspended from its lower end. The object is in equilibrium at position a. If a force is applied to pull the object downward by a distance x to position b, what is the elastic force of the spring at this time?
A. kx
B. mg+kx
C. mg-kx
D. ... | 38,797 | |
C | (GradeSchool) Science | MMK12-d56c8c23-4a29-4780-bb41-d41cfe524fa5 | <image>
As shown in the figure, an underground telephone cable of length L consists of a pair of wires AB and CD. These wires short circuit at point P along their length. A technician measures the resistance between AC to be R$_{1}$ and the resistance between BD to be R$_{2}$. The distance from point P to the AC end is... | 38,798 | |
C | (GradeSchool) Science | MMK12-87cb1142-cf2f-4142-8551-b1300511e400 | <image>
A student uses the spring exerciser shown in the figure for exercise. He finds that pulling with 5 springs is too difficult, so he removes 2 springs. If he pulls the remaining springs with a force of $300N$ and finds that the springs extend by $40cm$, assuming the spring constant and original length of each spr... | 38,799 | |
C | (GradeSchool) Science | MMK12-7b9c905c-ba02-4793-aaf7-656100384aef | <image>
As shown in the figure, a lightweight spring is placed vertically on a horizontal surface with a mass of $6kg$ object $A$ resting on its upper end, in a stationary state. Now, a mass of $4kg$ object $B$ is gently placed on top of object $A$, and the spring remains within its elastic limit. Taking $g$ as $10m/s^... | 38,800 | |
C | (GradeSchool) Science | MMK12-ada18a02-71ce-4282-9225-3b9cb6ea2ea4 | <image>
A smooth quarter-circle trough with a radius of $$R$$ is fixed in a vertical plane, within a region of electric field strength $$E$$ and magnetic field strength $$B$$, as shown in the figure. A positively charged small object with a charge-to-mass ratio of $$g\over 2E$$ starts from rest at the top of the trough... | 38,801 | |
A | (GradeSchool) Science | MMK12-ad957c88-8b16-4f2a-bfc0-885c14a546c0 | <image>
As shown in the figure, a block with mass $m$ is placed on a board with mass $M$, and the board is connected to a spring. Together, they perform simple harmonic motion on a smooth horizontal surface. During the vibration process, there is no relative motion between $m$ and $M$. Let the spring constant be $k$, a... | 38,802 | |
B | (GradeSchool) Science | MMK12-af4d63d3-32f3-4dc2-a296-7e4cf84b2a60 | <image>
In an experimental class, two students each pull a light spring with a horizontal force of F = 30N, as shown in the figure. If the original length of the spring is 12cm and the spring constant k = 10^3 N/m, the length of the spring when both students are stationary is ( )
A. 18cm
B. 15cm
C. 9cm
D. 5cm | 38,803 | |
B | (GradeSchool) Science | MMK12-e588de8c-d4b0-43d5-a757-49ebf672cec7 | <image>
As shown in the figure, the 'Jiaolong' submersible, independently developed by our country, vertically ascends after completing a task. During a certain period, it can be considered to ascend with uniform deceleration. If within this period, the speed at the end of 4 seconds is 4 m/s less than the speed at the ... | 38,804 | |
A | (GradeSchool) Science | MMK12-0c6bd09c-5e29-4b7c-aa6f-84c49aec7a87 | <image>
As shown in the figure, two opposite inclined planes have angles of 37º and 53º, respectively. Two small balls are horizontally thrown from the vertex with the same initial speed, one to the left and one to the right, and both balls land on the inclined planes. If air resistance is neglected, the ratio of the m... | 38,805 | |
D | (GradeSchool) Science | MMK12-d91966b4-bae7-4827-acdf-44dcd8d96f3b | <image>
As shown in the figure, object A is in equilibrium under the action of concurrent forces F$_{1}$, F$_{2}$, and F$_{3}$. If F$_{2}$ is rotated counterclockwise by 60$^{\circ}$ (with all other forces remaining unchanged), the magnitude of the resultant force on object A becomes ( )
A. $_{3}$
B. $_{1}$ + F$_{3}$
... | 38,806 | |
A | (GradeSchool) Science | MMK12-052c2a4e-f6a3-4cef-9268-bc8bd49470b1 | <image>
As shown in the figure, a group of enthusiasts made a small parachute. The bottom of the canopy is a rigid circular ring with a radius of $$R$$. Four strings of equal length, each $$2R$$, are evenly attached to the ring. The other ends of the strings are connected together and a mass $$m$$ object is suspended f... | 38,807 | |
B | (GradeSchool) Science | MMK12-41818184-9f4e-4de9-8977-f09656a2f06a | <image>
As shown in the figure, a pulley is suspended from the lower end of a spring, and a thin string passes over the pulley with weights A and B attached to its ends. The mass of B is m$_{B}$ = 3kg, while the mass of A is uncertain. Both objects are suspended in the air and can move up and down. Neglect the mass and... | 38,808 | |
A | (GradeSchool) Science | MMK12-b950d8af-7f55-4dde-a1ea-80dc864266aa | <image>
As shown in the figure, a uniform electric field is directed horizontally to the left. A positively charged small object moves to the right along an insulating horizontal surface. When it passes point A, its kinetic energy is 100J. When it passes point B, its kinetic energy has decreased by 4/5 of its original ... | 38,809 | |
B | (GradeSchool) Science | MMK12-e6c9462d-3200-4d91-9b10-458dc665d52a | <image>
As shown in the figure, a small ball of mass m is suspended from point O by a light string of length l. The ball is slowly pulled from its equilibrium position P to a position where the string makes an angle θ with the vertical by a horizontal force F. The acceleration due to gravity is g. Which of the followin... | 38,810 | |
B | (GradeSchool) Science | MMK12-33aa70c1-9e5a-4954-a184-34f072534c63 | <image>
As shown in the figure, when the switch $K$ is open, a beam of light with photon energy of $3.5eV$ is used to illuminate the cathode $P$ of the photoelectric tube, and it is observed that the ammeter reading is not zero. When the switch is closed and the sliding rheostat is adjusted, it is found that when the v... | 38,811 | |
C | (GradeSchool) Science | MMK12-7bc7d0fe-64b0-4d38-99c6-5be83c516398 | <image>
As shown in the figure, the total mass of a cannon loaded with a shell is $$M$$, the mass of the shell is $$m$$, the cannon barrel is horizontally placed, and the shell is fired horizontally with a velocity relative to the ground of $$v_{0}$$, then the magnitude of the recoil velocity of the cannon is ( )
A. ... | 38,812 | |
B | (GradeSchool) Science | MMK12-1769c44d-8a3e-44b8-9e7e-58560c65cf02 | <image>
The figure below shows a solar panel found by a student. After being exposed to sufficient light for a long time, measurements were taken and it was found that the voltage between the two terminals is 0.6V when no load is connected, and the current is 0.3mA when short-circuited. Then ( )
A. The electromotive f... | 38,813 | |
A | (GradeSchool) Science | MMK12-b8d4ab43-e10a-451d-98ea-9a4e46087ba7 | <image>
A cart is pulled along a horizontal surface at a constant speed using a pulley system as shown in the figure. The weight of the cart is $G=\text{10N}$, and the force applied is $F=\text{15N}$. The mechanical efficiency of the system is 60%. What is the frictional force between the cart and the ground?
A. 27N
B... | 38,814 | |
C | (GradeSchool) Science | MMK12-947cd5ab-c1cc-4f3f-b82a-376f2809526b | <image>
Through long-term observation, people have discovered 'binary star systems' in the universe. A 'binary star system' consists of two stars that are relatively close to each other, with each star's diameter being much smaller than the distance between the two stars, and the binary star system is generally far fro... | 38,815 | |
B | (GradeSchool) Science | MMK12-a1f123c1-bce8-402c-b094-fd1eeab7446d | <image>
As shown in the figure, there are three wooden blocks 1, 2, and 3 with masses m$_{1}$, m$_{2}$, and m$_{3}$, respectively, on a horizontal conveyor belt. Blocks 1 and 2, and blocks 2 and 3 are connected by light springs with original lengths of L and spring constants of k. The coefficient of kinetic friction be... | 38,816 | |
A | (GradeSchool) Science | MMK12-41e19c5a-7ccb-4719-9bf0-632873c1965e | <image>
A potentiometer is a type of variable resistor, as shown in the diagram. It is a resistive component with three terminals, and its resistance value can be adjusted according to certain rules. The carbon film resistor is made of uniform material of the same kind. In an experiment, it is connected to a power supp... | 38,817 | |
D | (GradeSchool) Science | MMK12-38488331-24d0-427b-bebe-531ffa4496aa | <image>
In the circuit shown in the figure, when switch S$_{1}$ is open and switch S$_{2}$ is closed, the voltmeter reads 3V; when both switches S$_{1}$ and S$_{2}$ are closed, the voltmeter reads 1.8V. Given that the voltmeter is an ideal voltmeter, the external resistance is R, and the internal resistance of the powe... | 38,818 | |
B | (GradeSchool) Science | MMK12-a8b00b6b-b835-425b-8534-5d53cbc644d0 | <image>
As shown in the circuit diagram, all meters are ideal meters, and ${{R}_{2}}=r$. When the switch S is closed and the slider P is moved to the left, the readings of the four meters all change. Let the readings of ${{A}_{1}}$, ${{A}_{2}}$, ${{V}_{1}}$, and ${{V}_{2}}$ at the same moment during the sliding process... | 38,820 | |
B | (GradeSchool) Science | MMK12-d2861e50-5408-4c2e-896f-ee00248caf75 | <image>
As shown in the figure, Xiao Li is riding on a high-speed train. When the carriage he is in is about to enter a tunnel, he sees the speed displayed on the screen as $216\:km/h$. He immediately observes the second hand of his watch, and after $20\:s$, the carriage exits the tunnel. The length of the tunnel is ap... | 38,821 | |
D | (GradeSchool) Science | MMK12-a5f3d3a2-bdd7-470b-9abe-a4ba94ca8bf4 | <image>
As shown in the figure, a light spring is fixed at the left end of a long wooden board m$_{2}$, and its right end is connected to a small wooden block m$_{1}$. The contact surfaces between m$_{1}$ and m$_{2}$, and between m$_{2}$ and the ground, are smooth. Initially, both m$_{1}$ and m$_{2}$ are at rest. Now, ... | 38,822 | |
B | (GradeSchool) Science | MMK12-eb657279-4b2b-4cd6-9e0d-45ade2f4b3b8 | <image>
As shown in the figure, two parallel metal rails are sufficiently long (negligible resistance) and fixed on an insulating horizontal plane. There is a uniform magnetic field perpendicular to the plane of the rails, with a magnetic induction intensity of $B$. A capacitor with capacitance $C$ is connected to the ... | 38,823 | |
A | (GradeSchool) Science | MMK12-a85ccac2-a00c-492d-a36f-f3d235b2fa7e | <image>
As shown in the figure, a cart of mass m is in contact with a vertical wall on its left side but is not fixed. The left side AB of the cart is a $\frac{1}{4}$ smooth circular track with a radius of R. The lowest point B of the track is tangent to the horizontal rough track BC, where $BC=2R$. A block of mass m (... | 38,824 | |
B | (GradeSchool) Science | MMK12-cb1ab65b-58e8-4b72-a6f6-5a675b379c3e | <image>
As shown in the figure, the reading of the spring balance is ( )
A. $$2.4\ \unit{N}$$
B. $$2.8\ \unit{N}$$
C. $$3.0\ \unit{N}$$
D. $$5.0\ \unit{N}$$ | 38,825 | |
C | (GradeSchool) Science | MMK12-db666b14-d378-4ff2-839d-33cbf226266e | <image>
A process for capturing $$CO_2$$ from flue gas is shown in the diagram. At room temperature, a $$0.1\ mol\cdot L^{-1}\ KOH$$ solution is used to absorb $$CO_2$$. If the volume change of the solution caused by the introduction of $$CO_2$$ and the evaporation of $$H_2O$$ can be ignored, the concentration of carbo... | 38,826 | |
C | (GradeSchool) Science | MMK12-5ba62a6f-af35-440b-beab-12983913a525 | <image>
The steps to prepare a commonly used industrial salt $$\text{C}$$ from partially oxidized metal shavings $$\text{A}$$ are as follows: Dissolve $$\text{C}$$ in water, add $$\ce{NaOH}$$ solution dropwise, a white precipitate appears, which gradually turns reddish-brown. Which of the following judgments is correc... | 38,827 | |
C | (GradeSchool) Science | MMK12-7285bb8a-6938-4c93-8b26-c49aea80ae1f | <image>
At a certain temperature, solutions of $$HCl$$ and $$CH_3COOH$$ with the same $$pH$$ and volume are diluted with water. The change in $$pH$$ with the volume of added water is shown in the figure. Which of the following statements is correct? ( ).
A. Curve II represents the dilution process of $$HCl$$
B. The d... | 38,828 | |
A | (GradeSchool) Science | MMK12-5da1fd91-d223-4a8b-97c1-e91c62b5cec8 | <image>
The solubility curve of silver bromate $$(\ce{AgBrO_{3}})$$ as a function of temperature is shown in the figure. Which of the following statements is incorrect? ( )
A. The dissolution of silver bromate is an exothermic process.
B. The dissolution rate of silver bromate increases with rising temperature.
C. At... | 38,829 | |
C | (GradeSchool) Science | MMK12-c3f674dd-43ff-4c9f-b901-0a49dd157c47 | <image>
At $$\ce{25℃}$$, a $$\quantity{0.1}{mol\cdot L^{-1}}\ce{HCl}$$ solution is added dropwise to $$\quantity{10}{mL}$$ of a $$\quantity{0.1}{mol\cdot L^{-1}}\ce{Na2CO3}$$ solution, with a total volume of $$\quantity{20}{mL}$$. The change in the amount of carbon-containing particles in the solution with respect to t... | 38,830 | |
B | (GradeSchool) Science | MMK12-875bfad2-99a7-46b9-881d-7b19a7b15c44 | <image>
High-purity manganese carbonate is widely used in the electronics industry. It is prepared by wet processing of soft manganese ore (mainly composed of MnO₂, with small amounts of impurities such as Fe and Si). The process for preparing high-purity manganese carbonate is shown in the diagram. The impurity remova... | 38,831 | |
D | (GradeSchool) Science | MMK12-3ec12baa-cfd6-487e-9d42-9afb73d1dd7b | <image>
At a certain temperature, the equilibrium curve for the dissolution of $$AgCl(s)\rightleftharpoons Ag^+(aq)+Cl^-(aq)$$ in water is shown in the figure. Which of the following statements is correct? ( ).
A. Adding $$AgNO_3$$ can change the solution from point c to point d
B. Adding a small amount of water shif... | 38,832 | |
C | (GradeSchool) Science | MMK12-4768d272-937d-4664-a517-a46677fb709d | <image>
The diagram shows the solubility curves of two solid substances, A and B (without water of crystallization). Which of the following statements is correct? ( )
A. The solubility of A is greater than that of B
B. At $$a_{1} \unit{\degreeCelsius }$$, when the saturated solutions of A and B are heated to $$a_{2} ... | 38,833 | |
D | (GradeSchool) Science | MMK12-67e3c620-7b43-4cec-ad65-bac3e91b85e7 | <image>
The reaction for smelting iron in a blast furnace is: $Fe_{2}O_{3}\left(s\right)+3CO\left(g\right)\dfrac{ high\ temperature .}{ }2Fe\left(s\right)+3CO_{2}\left(g\right)$, the following statements are correct $\left( \right)$
A. Increasing the temperature slows down the reaction rate
B. When the reaction reach... | 38,834 | |
C | (GradeSchool) Science | MMK12-ff3c6a81-9df3-4655-9569-c648b77abc77 | <image>
At room temperature, a $$0.100\ mol/L\ NaOH$$ solution is used to titrate $$25.00 \ mL \ 0.100\ mol/L\ H_2C_2O_4$$ solution, and the resulting titration curve is shown in the figure (the volume of the mixed solution can be considered as the sum of the volumes of the solutions before mixing). Which of the follow... | 38,835 | |
C | (GradeSchool) Science | MMK12-28a72625-e720-491a-802c-c8db5391bf98 | <image>
At room temperature, hydrochloric acid with a concentration of $$\quantity{0.1}{mol\cdot L^{-1}}$$ is added dropwise to a solution of $$\ce{Na_{2}CO3}$$. The curve showing the change in the solution's $$\ce{pH}$$ with the volume of hydrochloric acid added is shown in the figure. Which of the following statement... | 38,836 | |
D | (GradeSchool) Science | MMK12-f37a5ef6-3815-47cc-813c-bdf152b47a1e | <image>
An artificial kidney can use an electrochemical method to remove urea $$[\ce{CO(NH_{2})_{2}}]$$ from metabolic waste. The principle is shown in the diagram. Which of the following statements is correct? ( )
A. $$\text{B}$$ is the positive electrode of the power source.
B. After electrolysis, the $$\ce{pH}$$ o... | 38,837 | |
B | (GradeSchool) Science | MMK12-ece06567-8142-4b69-8198-1f0b570b802f | <image>
There is a reversible reaction: 2A(g) + 3B(g) xC(g) + 4D(g). If the reaction is carried out in a closed container with the same temperature and volume according to the following two ratios: 1. 0.8 mol A + 1.2 mol B + 1.2 mol C + 2.4 mol D 2. 1.4 mol A + 2.1 mol B + 0.6 mol C + 1.2 mol D. After reaching equilib... | 38,838 | |
D | (GradeSchool) Science | MMK12-e58c5458-424a-485a-9000-8dccc8403021 | <image>
In a sealed container of $$\quantity{2}{L}$$, $$\quantity{7.6}{mol}\ \ce{NO}$$ and $$\quantity{3.8}{mol}\ce{O_{2}}$$ are introduced, and the following reactions occur: 1. $$\ce{2NO(g) +O_{2}(g) \xtofrom{}2NO_{2}(g)}$$ 2. $$\ce{2NO_{2}(g) \xtofrom{} N_{2}O_{4}(g)}$$ The concentration changes of $$\ce{NO_{2}}$$ a... | 38,839 | |
C | (GradeSchool) Science | MMK12-259aa211-4a85-4094-aa45-01b786594a80 | <image>
The rare earth element cerium (Ce) mainly exists in monazite, and metallic cerium has very active chemical properties. In recent years, it has been discovered that cerium (Ce) oxides can efficiently produce H$_{2}$, with the preparation principle shown in the figure. It is known that 0<$\delta $<2. Which of the... | 38,840 | |
D | (GradeSchool) Science | MMK12-cae589d1-00ad-40e0-b716-73429e05fac9 | <image>
The layered structure of graphite is shown in the diagram. In the layered structure, the ratio of the number of carbon atoms, C—C bonds, and six-membered rings is ( )
A. $$1:1:1$$
B. $$2:2:3$$
C. $$1:2:3$$
D. $$2:3:1$$ | 38,841 | |
C | (GradeSchool) Science | MMK12-42175edf-461f-40d3-9c3a-3a4c88c812ea | <image>
In a closed container, there is a freely sliding partition in the middle, dividing the container into two parts. When the left side is filled with $$1 \ mol\ N_2$$ and the right side is filled with a mixture of $$8 \ g\ CO$$ and $$CO_2$$, the partition is positioned as shown in the figure, with the volume ratio... | 38,842 | |
C | (GradeSchool) Science | MMK12-5ae449e9-144d-4a17-96ea-77373f7b401b | <image>
At ${\rm 25℃}$, the relationship between the concentration of chromium-containing species in a ${\rm K_{2}Cr_{2}O_{7}}$ solution and the solution's ${\rm pH}$ (partial view) is shown in the figure. In the ${\rm K_{2}Cr_{2}O_{7}}$ solution, the following equilibrium exists: ${\rm Cr_{2}O_{7}^{2-}}$ (orange) ${\r... | 38,843 | |
C | (GradeSchool) Science | MMK12-608197a2-8515-4e4a-af7b-1908c2bfbcb1 | <image>
Correct experimental procedures are crucial for both experimental results and personal safety. Which of the following experimental operations is correct? ( )
A. Heating a liquid
B. Testing if oxygen is full
C. Reading the volume of a liquid
D. Measuring $$9.5 mL$$ of liquid | 38,844 | |
C | (GradeSchool) Science | MMK12-02754272-8851-4ffe-8b71-adb13c385cd7 | <image>
It is known that when 1 g of hydrogen gas completely combusts to form liquid water, it releases 143 kJ of heat, and when 18 g of water vapor condenses into liquid water, it releases 44 kJ of heat. Other relevant data is shown in the table: Then the value of X in the table is ().
A. 920
B. 557
C. 436
D. 188 | 38,845 | |
C | (GradeSchool) Science | MMK12-e364571d-3d96-495f-a7d0-ba09d2c430b6 | <image>
At ${\rm 25℃}$, in the aqueous solution system of "${\rm H_{2}A-HA^{-}-A^{2-}}$", the relationship between the mole fraction ${\rm (α)}$ of ${\rm H_{2}A}$, ${\rm HA^{-}}$, and ${\rm A^{2-}}$ with the solution's ${\rm pH}$ is shown in the figure. Which of the following statements is correct? ${\rm (\quad)}$
A.... | 38,846 | |
C | (GradeSchool) Science | MMK12-23ce351e-eadc-40f1-927d-1a5161622748 | <image>
The reaction for industrial synthesis of ammonia is: ${\rm N_{2}(g)+3H_{2}(g)⇌2NH_{3}(g)\triangle H=-92.4kJ\boldsymbol{⋅}mol^{-1}}$. The reaction process is shown in the figure. Which of the following statements is incorrect? ${\rm (\quad)}$
A. Process ${\rm Ⅱ}$ absorbs energy, and process ${\rm Ⅲ}$ releases ... | 38,847 | |
C | (GradeSchool) Science | MMK12-60b020ef-4481-4818-aaa9-5509a68243fe | <image>
The combustion of sulfur-containing coal produces atmospheric pollutants. To control this pollution, a factory has designed a new pollution control method that also yields chemical products. The process flow is shown in the diagram. Which of the following statements is correct? ${\rm (\quad)}$
A. The only eleme... | 38,848 | |
B | (GradeSchool) Science | MMK12-033fae05-4f4d-4474-8b5a-5ca1ee14c5ff | <image>
${\rm Z}$, ${\rm Y}$, ${\rm X}$, ${\rm W}$, and ${\rm Q}$ are five short-period main group elements with increasing atomic numbers. Among them, ${\rm Z}$, ${\rm Y}$, and ${\rm W}$ are located in three different periods, ${\rm Y}$ and ${\rm Q}$ are in the same group, and the number of outermost electrons in ${\r... | 38,849 | |
D | (GradeSchool) Science | MMK12-93e80b5c-71fc-4732-acd5-dd849f4159f7 | <image>
A certain acid $$\ce{HX}$$ dilute solution and a certain base $$\ce{YOH}$$ dilute solution have equal molar concentrations. After mixing the two solutions, the $$\ce{pH}$$ of the solution is greater than $$7$$. The reasonable judgment in the table below is ( )
A. 1.3.
B. 2.3.
C. 1.4.
D. 2.4. | 38,850 | |
B | (GradeSchool) Science | MMK12-4d523564-8b69-4aaa-b306-06774de4fe6a | <image>
The diagram shows the apparatus for the electrolysis of water experiment. Which of the following statements about this experiment is incorrect?
A. This experiment can be used to verify the composition of water.
B. Gas B can burn in air.
C. The chemical equation for the electrolysis of water is $$2H_{2}O \over... | 38,851 | |
B | (GradeSchool) Science | MMK12-e419b4db-34ec-4394-be2b-c2d1efd4a679 | <image>
In the molecule of toluene ( ), an organic compound is formed when one hydrogen atom on the benzene ring is replaced by a $$-\ce{C_{4}H_{9}}$$ group. How many such compounds are there? ( )
A. $$8$$ types
B. $$12$$ types
C. $$10$$ types
D. $$16$$ types | 38,852 | |
C | (GradeSchool) Science | MMK12-03792c29-b7d9-433a-b24b-bfa03c482cad | <image>
The schematic diagram of the chlor-alkali industry principle is shown in the figure. Which of the following statements is correct? ${\rm (\quad)}$
A. ${\rm M}$ is the negative electrode
B. The substance collected at outlet ${\rm c}$ is hydrogen gas
C. After a period of electrification, the ${\rm pH}$ in the cat... | 38,853 | |
D | (GradeSchool) Science | MMK12-cff71933-51de-40c0-8a3b-b81f7a13ac27 | <image>
At a certain temperature, in a $$\quantity{2}{L}$$ sealed container, the curves of the amount of substances of three gaseous substances $$\text{X}$$, $$\text{Y}$$, and $$\text{Z}$$ changing over time are shown in the figure. Which of the following descriptions is correct? ( )
A. From the start of the reaction... | 38,854 | |
B | (GradeSchool) Science | MMK12-c5160fb4-48ab-4b65-863d-3842e39e2371 | <image>
To study the respiration mode of yeast, a biology group created the apparatus shown in the figure from a to f. Which of the following judgments is unreasonable? ().
A. If the droplet in apparatus a does not move and the droplet in apparatus b moves to the right, it indicates that the yeast is only undergoing ... | 38,855 | |
B | (GradeSchool) Science | MMK12-d4c72052-8bbe-4288-afc2-8c550eac0232 | <image>
As shown in Figure 1, there is a primary spermatocyte of a certain organism, and Figure 2 shows five sperm cells of the organism. Based on the types and numbers of chromosomes in the figures, determine which are most likely to come from the same secondary spermatocyte ( )
A. 1, 2
B. 2, 4
C. 3, 5
D. 1, 4 | 38,856 | |
D | (GradeSchool) Science | MMK12-00fcc2bc-db87-40a9-adbb-a314f475462b | <image>
Researchers discovered that two plant species, Plant A and Plant B, can undergo interspecific hybridization (sexual reproduction between different species to produce offspring). Both plants contain 14 chromosomes, but their chromosomes are non-homologous. Flower color in both plants is controlled by a pair of a... | 38,857 | |
D | (GradeSchool) Science | MMK12-3ac546b6-19b1-4e64-8661-2658d6f9d999 | <image>
Using oat seedlings, the following two experiments were conducted: 1. In the first experiment, as shown in diagram A, the cut coleoptile tip $$C$$ is placed horizontally, with two agar blocks $$A$$ and $$B$$ placed closely on the cut surface of $$C$$. After several hours, they are treated as shown in diagram A;... | 38,858 | |
D | (GradeSchool) Science | MMK12-7701d1a1-6e8d-47ef-90e7-f73938d877e3 | <image>
CDK1 is a key protein that drives the cell from interphase to mitosis. After DNA replication begins, CDK1 becomes phosphorylated, leading to its activity being inhibited. Once DNA replication in the cell is complete and the materials are fully prepared, the phosphorylated CDK1 undergoes dephosphorylation and is... | 38,859 | |
D | (GradeSchool) Science | MMK12-b82347f1-4ae0-4348-8457-2ee5fef8d56a | <image>
A student wants to measure the photosynthesis rate of chloroplasts in plant leaves and conducts the experiment as shown in the diagram. A girdling treatment is applied at the base of the petiole (only restricting the input and output of organic substances in the leaf). At different times, leaf discs with an are... | 38,860 | |
B | (GradeSchool) Science | MMK12-12d048cf-5ad6-4b74-a19d-bdee03adfade | <image>
In a certain experiment, the deflection of the sensitive galvanometer needle is shown in Figure 1. Now, connect the two poles a, c, d, e of the sensitive galvanometers A<sub>1</sub> and A<sub>2</sub> to the outside of the nerve fiber membrane. When an appropriate intensity of stimulus is applied at point b, the... | 38,861 | |
C | (GradeSchool) Science | MMK12-cd9947c0-34dd-4876-b818-83d5f942813f | <image>
PCNA is a type of protein found only in proliferating cells, and its concentration changes as shown in the figure. Which of the following inferences is incorrect?
A. NA replicates during interphase
B. CNA is the result of selective gene expression
C. The synthesis of CNA and the replication of DNA require the... | 38,862 | |
D | (GradeSchool) Science | MMK12-048fe1c7-3fa4-48bd-944a-0946cb6e3e37 | <image>
In test tubes 1, 3, and 5, add 2mL of distilled water respectively. In test tubes 2, 4, and 6, add 2mL of homogenized germinated wheat seed solution respectively. Then, add an appropriate amount of Fehling's reagent to test tubes 1 to 4, and add an appropriate amount of Biuret reagent to test tubes 5 and 6. Sha... | 38,863 | |
B | (GradeSchool) Science | MMK12-7e5b87c4-6cfe-446a-adf9-0ac37b15cf50 | <image>
In the two pairs of contrasting traits of pumpkin shape and fruit color, white fruit is dominant over yellow, and disc-shaped fruit is dominant over spherical. The phenotypes of the F<sub>1</sub> generation from a cross between two parent pumpkins are shown in the figure. If the white disc-shaped F<sub>1</sub> ... | 38,864 | |
D | (GradeSchool) Science | MMK12-1fb494d5-c316-4f09-99da-97e2cf751c9f | <image>
In a certain spermatogonium, m and n are a pair of homologous chromosomes, where m is a normal chromosome, and A to E represent genes. A special process occurs after the synapsis of this pair of homologous chromosomes, as shown in the diagram, where the chromosomal bridge randomly breaks during division, and th... | 38,865 | |
B | (GradeSchool) Science | MMK12-529d70fe-c43d-4d65-a5e0-59f28c655ceb | <image>
As shown in the figure, the 'Ice Bucket Challenge' is a charitable activity aimed at raising awareness about a rare disease known as 'ALS' (Amyotrophic Lateral Sclerosis), while also raising funds to help with treatment. When a bucket of ice water is poured over the head, a normal body will react in a series of... | 38,866 | |
D | (GradeSchool) Science | MMK12-e6d8fd59-2e5f-47ad-b80d-4289cf19453a | <image>
In the diagram, Figure 1 represents the absorption and release curve of $$\ce{CO_{2}}$$ by a cotton plant over a day and night on a sunny day in August; Figure 2 shows four physiological activity states of two organelles in the mesophyll cells of cotton. Which physiological activities shown in Figure 2 occur se... | 38,867 | |
D | (GradeSchool) Science | MMK12-07a819ec-a129-4ea5-ae0c-b73b2ba9688d | <image>
Research has found that early-onset Alzheimer's disease is closely associated with the apolipoprotein E (ApoE) gene. The ApoE gene is located on chromosome 19 and has three common alleles: ApoE2, ApoE3, and ApoE4. ApoE4 can inhibit the functions of ApoE2 and ApoE3, while also reducing the stability of neuronal ... | 38,868 | |
C | (GradeSchool) Science | MMK12-ba0edcd6-f146-43b1-8aba-1c175421b9a4 | <image>
The sex chromosomes of male birds are ZZ, and those of female birds are ZW. In a certain bird species (2N=80), feather color is controlled by three genes located on the Z chromosome (as shown in the figure). D<sup>+</sup> controls gray-red color, D controls blue color, and d controls chocolate color. D<sup>+</s... | 38,869 |
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