Write down the following chemical reactions (1) Light yellow solid combustion_____________________________________________ (2) Preparation of oxygen by heating pure substance in laboratory_____________________________________________ (3) Heated light green powder_____________________________________________ (4) A metal burns in air_____________________________________________ (5) Reaction of producing colorless and odorless gas after combustion_________________________________________

Write down the following chemical reactions (1) Light yellow solid combustion_____________________________________________ (2) Preparation of oxygen by heating pure substance in laboratory_____________________________________________ (3) Heated light green powder_____________________________________________ (4) A metal burns in air_____________________________________________ (5) Reaction of producing colorless and odorless gas after combustion_________________________________________

(1) Light yellow solid burning sulfur + oxygen = = ignition = = sulfur dioxide (2) heating pure substance to produce oxygen potassium permanganate in laboratory = = heating = = potassium manganate + manganese dioxide + oxygen (3) heating light green powder basic copper carbonate = = heating = = copper oxide + carbon dioxide + water (4) burning a metal in air with sodium + oxygen = = ignition = =

Find the following chemical reaction literal expression
1. Drop hydrochloric acid on the marble
2. Magnesium strip combustion
3. Blow air to clarified lime water
4. Nitrogen and oxygen generate nitric oxide under discharge condition
5. Black powder [raw material sulfur, charcoal, potassium nitrate] ignites and reacts to form potassium sulfide, carbon dioxide and nitrogen

1. CaCO3 + 2HCl = CO2 + H2O + CaCl2, calcium carbonate + hydrochloric acid = CO2 + water + calcium chloride 2. 2mg + O2 = 2MgO, magnesium + oxygen = magnesium oxide 3. CO2 + Ca (OH) 2 = CaCO3 + H2O, carbon dioxide + calcium hydroxide = calcium carbonate + water 4. N2 + O2 = 2No, nitrogen + oxygen = nitric oxide 5. S + 3C + 2kno3 = K2s + 3co2 + N2, sulfur + carbon + nitrate

Write down the expressions and phenomena of the following chemical reactions
1. Iron burns in oxygen
2. Sulfur burns in oxygen
3. Phosphorus burns in oxygen
4. Magnesium burns in oxygen
5. Carbon burns in oxygen
6. Aluminum burns in oxygen
7. Hydrogen burns in oxygen
8. Sodium burns in chlorine
9. Respiration
10. Water electrolysis
11. Decomposition of hydrogen peroxide
12. Decomposition of potassium permanganate
13. Decomposition of potassium chlorate
14. Mercuric chloride decomposes when heated

Iron + oxygen → (ignite) Fe3O4
3Fe + 2O2 = ignition = Fe3O4
Mars splashes and forms a black solid
Sulfur + oxygen → (ignite) sulfur dioxide
S + O2 = ignition = SO2
It has a blue purple flame and a pungent smell
Phosphorus + oxygen → (ignite) phosphorus pentoxide
4O + 5o2 = ignition = 2p2o5
White flame, white smoke
Magnesium + oxygen → (ignite) magnesium oxide
2mg + O2 = ignition = 2MgO
Produce dazzling white light and white solid
Carbon + oxygen → (ignite) carbon dioxide
C + O2 = ignition = CO2
Yellow flame
Aluminum + oxygen → (ignite) aluminum oxide
4Al + 3O2 = ignition = 2al2o3
Produce dazzling white light and white solid
Hydrogen + oxygen → (ignite) water
2h2 + O2 = ignition = 2H2O
The light blue flame is covered on the flame with a beaker, and water droplets are formed on the wall of the beaker
Sodium + chlorine → (ignite) sodium chloride
2Na+Cl2=2NaCl
Emit white light to form white solid
Respiratory function: not very clear
Water → (power on) hydrogen + oxygen
2H2O = power on = 2h2 ↑ + O2 ↑
Bubbles are generated on the two electrodes to collect the gas from the two electrodes. The volume ratio of positive gas to negative gas is about 1:2,
Hydrogen peroxide → (MnO2 catalyzed) water + oxygen
2H2O2=MnO2=2H2O+O2↑
Phenomenon: bubbles
Potassium permanganate is divided into potassium permanganate → (heated) potassium permanganate + manganese dioxide + oxygen
2kmno4 = heating = MnO2 + k2mno4 + O2 ↑
Dark purple solid turns brown black solid (that's all you can see)
Potassium chlorate potassium chlorate → (heated) potassium chloride + oxygen
2kclo3 = heating / MnO2 = 1kcl + 3O2 ↑
Mercury oxide is divided into mercury oxide → (heating) mercury + oxygen
2hgo = heating = 2hg + O2
The red solid turns into a silver white liquid

What is the frequency, frequency distribution and group distance

Frequency the number of occurrences of each object is frequency
Frequency distribution frequency in each range class
The distance between the highest value and the lowest value of each group. In grouping statistics, the size of a group may vary according to the total distance of the number in the series and the number of groups to be divided. The minimum limit of each group is called the lower limit, and the maximum limit is called the upper limit. The distance between the lower limit and the upper limit is the group distance

(1) In the frequency distribution table of 120 data, the sum of the frequency of each group is equal to______ The sum of the frequencies of each group is equal to______ .
(2) If the range of data 3, x, - 1 is 5, then the value of X is______ .

(1) In the frequency distribution table of 120 data, the sum of frequency of each group is equal to 120, and the sum of frequency of each group is equal to 1
(2) If the range of data 3, x, - 1 is 5, then the value of X is - 2 or 4

Mathematical probability problems in grade two of junior high school
Select any point P in the square ABCD with side length of 1 and connect PA and Pb respectively to form △ PAB
Find the probability that the area of △ PAB is less than 1 / 4
Find the probability that the area of △ PAB is between 1 / 6 and 1 / 5

Find the probability that the area of △ PAB is less than 1 / 4
Divide 1 / 4 by 1 to get a probability of 1 / 4
Find the probability that the area of △ PAB is between 1 / 6 and 1 / 5
1/5-1/6=1/30

If you buy a sports lottery, you can get a grand prize of 5 million yuan. The winning rules are as follows: if the number of the lottery you buy is exactly the same as that of the lottery, you can get the prize. The lottery number is obtained by the following methods: put the 0-9 number (a total of 7 groups) into seven number shakers, and number them with numbers (1-7). It is stipulated that the number shaken by the first machine is the first, and the number shaken by the second machine is the second The number is the second digit The number on TV 7 is the seventh. Please analyze. What's the probability of winning a special prize when you buy a sports lottery______ ．

When buying a sports lottery, the probability of winning a special prize is a classical probability. All the events in the experiment are known by the principle of step-by-step counting, and there are 107 results. One event meets the conditions. The probability of winning a special prize is p = 1107

There are four line segments with lengths of 1, 3, 5 and 7 respectively. If any three of the four line segments are selected, the probability that the three line segments can form a triangle is ()
A. 14B. 13C. 12D. 25

Taking any three of the four line segments, there are C34 cases in total. Only when 3, 5 and 7 are taken, can a triangle be formed. Therefore, the probability that the three line segments can form a triangle is p = 14

1. There is a stall promoter who puts eight white and eight black go pieces in a bag. He stipulates that anyone who is willing to play the game will pay 1 yuan as a "handling fee" and then take five pieces out of the bag. The winning situation is as follows:
Five white chess, four white chess, three white chess, others
No prize for 20 yuan, 2 yuan and 0.5 yuan
Try to calculate: (1) the probability of being able to touch 20 yuan at a time;
(2) The probability of being able to touch 2 yuan at a time;
2. Suppose a family has five children, find the following probability
(1) What's the probability of five girls?
(2) What's the probability of three girls and two boys?
(3) What's the probability of at least one boy?

1. (1) the probability of getting 20 yuan at one time: the number of methods to get 5 out of 8 white words divided by the number of methods to get 5 out of 16 = [(8 * 7 * 6 * 5 * 4) / (5 * 4 * 3 * 2 * 1)] / [(16 * 15 * 14 * 13 * 12) / (5 * 4 * 3 * 2 * 1)] = 1 / 78 (2) the probability of getting 2 yuan at one time: the number of methods to get 4 out of 8 white words + the number of methods to get 8

What are the calculation formulas of high school probability?

There are two types
The principle of step counting is multiplication formula
The principle of classified counting is the formula of addition