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There are 94 students in the two classes of grade 6, including 39 girls. It is known that girls in class 1 account for 2 / 5 of the class and girls in class 2 account for 3 / 7 of the class, How many people are there in the two classes Wrong number. How many people are there in each class
If there are X students in class one, then there are 94 minus X students in class two
The equation: 2 / 5x + 3 / 7 (94-x) = 39
Just work it out
There are 42 students in class one of grade five. The number of girls is three fourths of that of boys. How many girls are there?
Boys: = 42 / (1 + 3 / 4) = 24
Female = 42 - 24 = 18
There are six less girls than boys in the class of six years. The number of girls is three-quarters of boys. How many boys and girls are there?
(Note: there are two questions in total. There are 42 students in the class of six years, and the number of girls is three-quarters of that of boys. How many boys and girls are there respectively? There are six girls less than boys in the class of six years, and the number of girls is three-quarters of that of boys. How many boys and girls are there respectively
There are 4 boys and 3 girls, 7 in total, 42 △ 7 = 6, boys = 4 × 6 = 24, girls = 3 × 6 = 18
On tree planting day, the school will plant 750 trees and divide the tasks into three classes of grade 5 according to the number of people. There are 40 students in class 1 of grade 5, 42 students in class 2 of grade 5 and 43 students in class 3 of grade 5
How many trees are there in each of the three classes?
One class 750 × 40 ÷ (40 + 42 + 45) = 240 trees
Class 2 750 × 42 ÷ (40 + 42 + 45) = 252 trees
Three classes 750 × 43 ÷ (40 + 42 + 45) = 258 trees
According to the chemical formula of sulfuric acid: H2SO4, it is calculated as follows: (1) the mass of sulfur in 49kg sulfuric acid; (2) the amount of oxygen in 16g sulfuric acid
(1) The mass fraction of S is 32 / 98, so the mass fraction of sulfur is 49 * 32 / 98 = 16KG
(2) 16 / (64 / 98) = 24.5
The chemical formula of sulfuric acid is H2SO4. Please calculate: what is the mass of hydrogen in 98g sulfuric acid
(1×2)÷（1×2+32+16×4）×98g=2g
What is the mass of sulfuric acid (H2SO4) containing 0.1g hydrogen?
A.9.8g
B.4.9g
C.49g
D.10.49g
If you are kind, please help me!
B. 4.9g
The molecular weight of sulfuric acid is 98, the atomic weight of its atom is 1, and each molecule of sulfuric acid contains two atoms of hydrogen
The chemical formula of sulfuric acid is known as H2SO4. Find 1, the relative molecular weight of sulfuric acid 2, the mass ratio of each element in sulfuric acid 3
The chemical formula of sulfuric acid is known as H2SO4
1. Relative molecular weight of sulfuric acid
2. Mass ratio of elements in sulfuric acid
3. Mass fraction of hydrogen in sulfuric acid
4.50 what is the mass of hydrogen element in sulfuric acid
The relative molecular weight of H2SO4 is 1. The relative atomic mass of H is 1. The relative atomic mass of S is 32. The relative atomic mass of O is 16. So the relative molecular mass of H2SO4 is 1 * 2 + 32 * 1 + 16 * 4 = 98
The mass ratio of hydrogen, sulfur and oxygen in sulfuric acid is 1 * 2:32:16 * 4 = 1:16:32
3. The mass fraction of hydrogen in sulfuric acid is 1 * 2 / (1 * 2 + 32 * 1 + 16 * 4) = 1:49
The mass of hydrogen element in 450 sulfuric acid is 50 * (1 * 2 / (1 * 2 + 32 * 1 + 16 * 4)) = 50 / 49, which is close to 1
If the mass of oxygen-containing elements in sulfur dioxide and sulfur trioxide is equal, the mass ratio of sulfur dioxide and sulfur trioxide is 0
The oxygen-containing elements have the same mass,
It means that there are equal numbers of oxygen atoms,
Three sulfur dioxide molecules and two sulfur trioxide molecules contain six oxygen atoms,
The mass ratio of sulfur dioxide to sulfur trioxide is 3so2: 2so3
＝3(32+2*16):2(32+3*16)
＝6:5
If the mass of oxygen element in sulfur dioxide and sulfur trioxide is equal, what is the mass ratio of sulfur dioxide and sulfur trioxide?
Can you make it clear
3 SO2
2 SO3
Every three sulfur dioxide molecules and two sulfur trioxide molecules contain the same number of oxygen atoms, so the mass of oxygen is equal
Mass ratio = [3 * (32 + 16 + 16)]: [2 * (32 + 16 + 16 + 16]
=6:5
RELATED INFORMATIONS
- 1. Can you see from the following two figures which school has more female students? Why? School a: male: 50%, female: 50% School B: male: 60%, female: 40%
- 2. There are 540 students in the fifth grade of experimental primary school. The number of boys is 1.2 times that of girls. How many boys and girls are there respectively?
- 3. Master Wang planned to process 120 parts today. In fact, he processed 7 / 12 of all the parts in the morning, 38 in the afternoon and 42 in the evening. That's a big deal How much of the task did Master Wang overfulfill on that day?
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- 9. 2,4,3,6,5, (), (), 18,17. What's the rule
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- 11. 1. The following is the number of each class in Grade 5 of Yucai primary school: Class 1: 39, class 2: 41, class 3: 40, class 4: 43, class 5: 12 Which classes can be equally divided into groups with the same number? Which classes can't? Why? 2. Fill in the blanks with prime numbers, which cannot be repeated: 18 = + = + = ++ 3. The difference between the minimum multiple of a number and its maximum factor is () 4. The quotient of the minimum multiple of a number divided by its maximum factor is () 5. If a natural number is smaller than 20, it is a multiple of 2 and has a factor of 7. This natural number is (). There are () factors for the difference of (); there are () factors for the product of a * B There are 42 students in class five
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