Conversion relations of the amount, mass, molar mass, particle number and Avogadro constant of matter (÷M) (×NA) Mass m --- → amount of matter n --- → number of particles N (×M) (÷NA) Particle number n --- → mass m --- → mass n (÷M) (×NA) Mass m --- → amount of matter n --- → number of particles N (×M) (÷NA) Particle number n --- → mass m --- → mass n

Conversion relations of the amount, mass, molar mass, particle number and Avogadro constant of matter (÷M) (×NA) Mass m --- → amount of matter n --- → number of particles N (×M) (÷NA) Particle number n --- → mass m --- → mass n (÷M) (×NA) Mass m --- → amount of matter n --- → number of particles N (×M) (÷NA) Particle number n --- → mass m --- → mass n

Matter is composed of particles, and each particle has its mass. Molar mass refers to the mass of 1mol of this material, and its unit is g / mol, i.e. mass / mass = molar mass (many definitions of mass can be obtained from its unit). So m △ M = n what you say: mass m (× Na) -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Formula conversion between quantities of chemical substances
Concentration of substance
Mass percent concentration
mass fraction
volume fraction
Mass fraction of matter
solubility

Derivation:
M1 is the mass of solute, M is the molar mass of solute, the amount of solute in solution N = M1 / M; M2 is the mass of solution, ρ is the density of solution, v = m2 / ρ. But in chemistry, the unit of mass is generally gram, and the unit of density is gram / cm3, so the unit of volume is cm3, and the unit of mass concentration is mole / L, which is converted into liter, so it is divided by 1000
Mass concentration C = n / v = (M1 / M) / [(m2 / ρ) / 1000]
The mass fraction is expressed by P%, P% = M1 / m2,
The conversion formula between the mass concentration and the mass percentage concentration of the substance is
c=1000ρP%/M

The passenger car and the freight car leave from both sides of a and B at the same time. It takes 10 hours for the passenger car to complete the whole journey and 15 hours for the freight car to complete the whole journey. After the two cars meet halfway, the passenger car runs another 96 kilometers. At this time, the passenger car completes 80% of the whole journey. How many kilometers are there between a and B?

Answer: the distance between a and B is 480 kilometers

Any number to the power of 0 is 1

The power of 0 is meaningless

Eight people were driven to the railway station by two cars. One of the cars broke down 15 km away from the railway station, and there were 42 minutes left before the train check-in time. At this time, the only available means of transportation was a car, including the driver. The average speed of the car was 60 km / h, and the pedestrian speed was 5 km / h
Please design a plan (not counting the time of getting on and off), so that all 8 people can arrive at the station in 42 minutes, and explain the reason with the relevant knowledge of the equation (if the time is less than 38 minutes, you can get 10 points, which is excellent. If the time is between 38 and 42, you can get 6 points, which is pass). What is your plan? Reasons and answers: (complete answers are rewarded) urgent

My answer is as follows:

What's three quarters minus one quarter

3/4-1/4=2/4=1/2

Make a load-bearing paper bridge with a piece of A4 paper,
The material is a piece of A4 paper, self-adhesive stickers, coins on the bridge and so on. There is no requirement for the length
I have never been in touch with this kind of production before. The competition is made on site. The heavier the load, the better,

I've never been in touch with it, but with imagination:
1. The shorter the paper bridge, the better
2. The paper bridge is W-shaped and stable
3. Paper bridge can't be folded many times, it's better to form at one time
You can go to Baidu's pictures to search for keywords under the load-bearing paper bridge
I just saw a lot of shapes

X - ½ = - three X + 2 to solve linear equation with one variable

X - ½ = - x + 2 / 3
Multiply both sides by six
6x-3=-2x+12
8x=15
x=15/8

The distance between a and B is 140 km. When a big car leaves from a place for 2 hours, a small car also leaves from a place
The distance between a and B is 140 km. Two hours after a big car leaves from a, a small car also leaves from A. as a result, the small car arrives 50 minutes later than the big car, and the speed of the big car is 2 / 3 of that of the small car

Think of the cart speed as 1
Then the car is 1 / 2 / 3 = 3 / 2
So the cart time is 3 / 2 times of that of the car
50 minutes is 5 / 6 hours
So there are 2-5 / 6 more cars = 7 / 6 hours
So the car time is 7 / 6 (3 / 2-1) = 7 / 3
Car speed 140 △ 7 / 3 = 60
60×2/3=40
A: the speed of the cart is 40 km / h

If AB is not equal to 0 and the square of a-ab-6b = 0, then the value of B out of a is 0