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?

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?

There are 550 students in the fifth grade of experimental primary school
Number of boys = 550 * 1.2 / (1 + 1.2) = 300
The number of female students = 550 * 1 / (1 + 1.2) = 250. Surround a flower bed by the wall. The fence around the flower bed is 46m long. Find the area of the flower bed? What shape is your flower bed? Give me a picture

Master Wang planned to process 120 parts on September 6. In fact, he processed 712 parts in the morning, 38 parts in the afternoon and 42 parts in the evening. What percentage of Master Wang's over fulfilled the task on this day?

120 × 712 + 38 + 42, = 70 + 38 + 42, = 150 (pieces); (150-120) △ 120, = 30 △ 120, = 25%; answer: in this way, Master Wang overfulfilled 25% of the task on this day

It is known that the chemical formula of sulfuric acid is H2SO4. Try to find: (1) the mass fraction of sulfur in sulfuric acid; (2) the hydrogen content of 98g sulfuric acid is equal to that of many grams of water; (3) the mass of oxygen in 36g water? (4) How many grams of water contain 5g of hydrogen?

(1) The mass fraction of sulfur in sulfuric acid is 3298 × 100% ≈ 32.7% (2) suppose the mass of water is x.98g × 1 × 298 = x × 1 × 218, the solution is x = 18G (3) 36g, the mass of oxygen in water is 36g × (1618 × 100%) = 32g (4) the mass of water is 5g × (1 × 218 × 100) = 45g

At present, 114.5g dilute sulfuric acid (mixture of sulfuric acid and water) contains 10.5G hydrogen element. How many grams of sulfuric acid and water are contained in dilute sulfuric acid? (please answer in detail)

Let the mass of H2O be X
The mass of H2SO4 is y
solve equations
2/18 x + 2/98 y = 10.5
x+y=114.5
have to
x=
y=

Please design an experiment to prove that the temperature of the outer flame of the alcohol lamp is the highest

Put the stick on the inside and outside of the alcohol lamp,
Measure the time from start to ignition
Short time indicates high temperature

Do alcohol lamps produce a lower temperature flame than matches

No, the temperature is higher than that of the match, because the alcohol lamp burns alcohol, while the match burns wood. Because the heat of alcohol is higher than that of wood, the flame temperature of the alcohol lamp will be higher than that of the match

Why is the flame layer temperature of alcohol lamp different

The normal use of alcohol lamp flame should be divided into three parts: flame core, inner flame and outer flame
Recent studies show that the order of flame temperature of alcohol lamp is: inner flame > outer flame > flame core
It is generally believed that the outside flame temperature of alcohol lamp is the highest,
The reason is that the contact area between alcohol vapor and oxygen is the largest and the combustion is the most sufficient;
At the same time, because the outer flame is in full contact with the outside atmosphere, the energy exchange with the environment is the easiest,
Heat loss is the most, resulting in the temperature of the inner flame is higher than that of the outer flame

What's the hottest part of the flame

Outer flame
From the outside to the inside

The three-layer flame of alcohol lamp has the highest temperature
According to the entry of "alcohol lamp" in the online encyclopedia, after scientific research, the temperature of the inner flame is higher than that of the outer flame, and there are other experimental researches on "the highest temperature of the inner flame" on the Internet,

It's true that the temperature of the inner flame is higher than that of the outer flame. It can be analyzed that the temperature of the inner flame is higher than that of the outer flame, but the full contact between the outer flame and the outside atmosphere should be more intense than that of the inner flame, so it will cause the illusion that the temperature of the outer flame is higher than that of the inner flame, and it will not be explored in the usual study

Can you prove that alcohol (C2H5OH) contains carbon and oxygen through experiments? Write out the test plan

Ignite and check the product. The product can make anhydrous copper sulfate blue, proving the existence of hydrogen; it can make clear lime water turbid, proving the existence of carbon