There are several science questions in the first year of junior high school, and there is one scienc

1. Thermal expansion and cold contraction.

2. Pacific Rim and Himalayas.

3, silver shirt, 9, c2h4

10. Each cycle, the beginning is a metallic element, [except for 1 cycle], the one near the tail is a non-metallic element, and the last one is a noble gas. As the atomic number increases, the number of electrons in the outermost shell of the atom ranges from 1 to 8....

11. The radius of an atom is determined by: the number of electron layers, the number of charges, and the number of electrons outside the nucleus. Since they are in the same period, the number of electron layers is the same, so there is a nuclear charge number, and their charge number gradually increases, and the stronger the binding force on the electrons outside the nucleus. That's why the radius is small.

12, the number of protons, the number of neutrons.

13 16,15.Concept: The number of protons is equal to the number of electrons outside the nucleus. Relative atomic mass = number of protons + number of neutrons.

14 Composed of CH4, it is the simplest organic matter.

15 The valence state that appears in matter.

16 +2 valence.

17 CO3 -2 valence.

There are a few biological, I've forgotten. Now that I'm in my third year, there's only so much I can think of. The current students are so diligent! Admire.

1.Thermal expansion and cold contraction 2Pacific Rim Mediterranean-Himalayas 3

Korean pine Longwhite larch 4Cell Tissue 5Angiosperms 6

Gymnosperms stem 7Rare reptiles - Chinese alligators, monitor lizards, pythons, rare angiosperms, goldenrod tea, ginseng, wangtianshu, rare gymnosperms, bald fir, silver fir, metasequoia, rare ferns, emeiar ferns, lotus leaf iron ferns, truncated shield fern 8Insects, arthropods, head, thorax, abdomen, 3, 2, 10

The number of electron layers is the same, the atomic radius gradually decreases, the metallicity gradually decreases, and the non-metallicity gradually increases11As the number of nuclear charges increases, the gravitational attraction of the outer electrons increases 12Number of protons Number of neutrons 15 14

Methane 15The property of a certain number of atoms of an element combined with a certain number of atoms of other elements is called the valency of this element. 16.

2 price 17(CO3-) 2-valent.

1.Thermal expansion and cold contraction.

2.The Pacific Rim, the Himalayas and the Mediterranean.

3.Silver fir, dove tree.

8.Insects, arthropods, head, thorax, abdomen, two, one.

1. Hot Zhang cold contraction, 3 silver fir 7, giant panda .........9 : C2H4 10 : The atomic radius of the same electron layer gradually decreases, the metallicity gradually decreases, and the non-metallicity gradually increases 11:

The main factor affecting the radius of an atom is the number of electron layers, followed by the number of nuclear charges, and again the number of electrons outside the nucleus. The number of electron layers in the same period is the same, so it is determined by the number of nuclear charges, and the more the number of nuclear charges, the stronger the attraction to the electrons outside the nucleus, resulting in the smaller the atomic radius, and vice versa, the larger. Therefore, this law is also followed from li to f.

12: number of protons; Neutron number 13: 16 , number of protons + number of neutrons = number of masses; 15, number of protons = number of nuclear charges = number of electrons outside the nucleus 14:

CH4Methane 15 is the valence state of the element in the compound. 16:+2 price 17:

CO3 valence + 2 valence.

There's only so much more to help you.

Xiao Ran Yijun. It's amazing.

Admire. Admire.

Big brother, have you played? Question 9, the elements on the left and right sides of the chemical equation are different, are you writing less? This is not in accordance with the law of conservation of mass, right?

Hehe: That's a good idea.

Come up and type a few words, no need to use your brain, and there is the right answer.

Really smart !

The questions in the first year of junior high school are so difficult! It seems that I am really old.

12 questions. Same number of protons, different number of neutrons.

13 questions. There are 16 neutrons inside the nucleus and 15 electrons outside the nucleus.

Because the mass of the electron is small, the relative atomic mass is about equal to the proton mass + neutron mass; Whereas, the number of electrons and the number of protons in an atom are equal.

1. Viscosity (viscosity is related to fluid temperature).

9、ch2=ch2

14. CH4 methane.

Isn't it, where are you? We didn't know the simple chemical formula in junior 2, I was depressed, I had studied it myself, and I didn't know what you wrote at all.

It's a lot of brains to ask for this percent.

Hehe, you have a lot of questions, but you already have good answers, and the senior brother who sent the mouse answered it okay Admire it, and the future is terrifying.

The 4th and 5th floors are very good! Japan's ** is in addition to the name! Xia Weiyi's is okay, and the one in East Africa is fierce

Oh, it's so hard, I don't even know about it in my second year of junior high school, let alone that.

The senior brother who sent the mouse is amazing, and he answered it all right, and the little sister supported it.

No way! Is there science in the first year of junior high school? Why didn't I read it?

1) What factors can speed up the dissolution of rock sugar.

2）1.The high temperature of the water can speed up the dissolution of rock sugar.

2.The small sugar grains can speed up the dissolution of rock sugar.

3.Stirring can speed up the dissolution of rock sugar.

3) Conjecture one.

Pour an equal amount of Li Zheng's water into two identical cups, one with 100 degrees Celsius and the other at 0 degrees Celsius. Add the same amount of sugar of the same size, and in the same environment, use a stopwatch to record the time when the rock sugar melts, record and compare, and draw conclusions.

4) Under the same conditions, the higher the water temperature, the faster the rock sugar melts.

1) What factors can speed up the dissolution rate of rock sugar.

Guess 1: Stir with chopsticks.

Guess 2: Heating.

Guess 3: Break it first and put it in the message.

3) Stir with chopsticks.

Divided into two groups of experiments with cups 1 and 2, under the same temperature, the same amount of water and rock sugar of similar size were added to the two cups, cup 1 was not stirred, and cup 2 was stirred.

Phenomenon: The dissolution rate of sugar in cup 2 is significantly faster than that in cup 1.

4) Conclusion: The method of stirring chopsticks can significantly improve the dissolution speed.

1.**Factors that speed up the dissolution of rock sugar.

2.For the same amount of rock sugar, the higher the temperature of the solution (soup), the faster the rock sugar will dissolve.

For the same amount of rock sugar, the smaller the rock sugar particles, the faster the dissolution rate.

For the same amount of rock sugar, the more solution, the faster the rock sugar will dissolve.

3.Conjecture 2: Take two parts of rock sugar in the same amount and appropriate, the first part of rock sugar is lumpy, and the second part is ground into small particles.

Add two parts of rock sugar to the same amount of water or soup at the same temperature (to avoid oversaturation), observe the time taken for the complete disappearance (dissolution) of the rock sugar particles and record them.

Comparing the length of time taken, the time taken for the first serving of rock sugar to completely dissolve was shorter than that of the second part, and the conclusion was reached.

4.For the same amount of rock sugar, the smaller the rock sugar particles, the faster it dissolves.

The valency of the hydrogen element is 1 1 sulfur trioxide molecule, containing 3 oxygen atoms and 2 hydrogen molecules.

Greater than CO, greater than C, greater than CH4

or H2O23SO2 2Hg 5N2

3h2+n2=2nh3

4fes+7o2=2fe2o3+2so2

nitrogen atoms, 1 hydrogen molecule, 2 nitrogen atoms, 1 carbonic acid molecule, 2 hydrogen atoms, 1 carbon dioxide molecule, 2 oxygen atoms.

c:o:n:h=3:4:7:1

na2s2o4

Hello! Choose C! If you have a tape measure in your hand, and an object is centimeters long, it is centimeters if you measure it normally, and then you stretch the ruler and measure it again, and then look at the ruler, it is only 23 centimeters. The principle is the same. Finally, I wish you all the best in your studies!

The length of the wooden ruler selected c for damp expansion is 23.

Larger than the original foot. The measurement will be smaller.

It should be d, because if you want to be completely accurate, there must be a gap in the measurement of an inaccurate ruler.

But if you don't choose D, you should choose C.

The value of the quantity is on the small side.