Help me do these questions, have a detailed process, and it is best to write down the formula

The number of hydrogen molecules in 23=

The number of chloride ions in .

The number of oxygen atoms in .

The molecular weight of water to the 24th power is 2mol

The amount of a substance of 23 iron atoms to the power of the two-third power.

1 n=n*na= (nAvogadro's constant.

2 n=1*

3 n=1*4*

4 n=5 n=

The fourth question is mass or quantity of matter? The amount of the substance is 2mol, and the mass is 2mol*18g mol=36g

You're too lazy to do this topic.

Distance on the graph: Actual distance = scale bar = 1 1000

It is known that the distance on the front side image is 5 cm long and 3 cm wide. Then the actual distance length should be: 5 (1 1000) = 5000 (cm) = 50 meters.

The actual width is: 3 (1 1000) = 3000 (cm) = 30 m blind.

Actual floor area: 50x30 = 1500 square meters for this oak.

The title tells you that the scale is 1 1000, which means that the actual length is 1000 times the length in the figure.

We find the length and width of the rectangle in proportions.

Set: Actually, the rectangular long-skinned cherry blossoms are ruled.

1：1000=5：x

x = 1000x5 1 = 5000 cm = 5 meters.

The width of the actual rectangle is y, then:

1：1000=3：y

y=1000 3 1=3000 cm=30 meters.

The actual area of the rectangle is based on the formula of the surface burning rock cluster of the rectangle, and the area of the rectangle = length and width.

1500 square meters.

If the scale is 1:1000, the actual length of the rectangular nano is a = 5 * 1000 = 5000 cm = 50 meters, and the width is b = 3 * 1000 = 3000 cm Que Song = 30 meters, then the actual area is s = a * b = 50 * 30 = 1500 square meters.

5 1 000 5000 (cm).

3 1 1000 3000 (cm).

5000 cm 50 meters, 3000 cm 30 meters.

50 30 1500 (sq.m.).

Answer: The actual seepage area is 1,500 square meters. Sullen talk.

The logarithmic identity refers to the Sen type of Wang rot: sleepy and leaky ln(e a)=a, e lna=a

ln(e^ln3-1)-ln(e^ln2-1)ln(3-1)-ln(2-1)

ln2.

x 2 3x-40 = 0 delta = 3 2-4 1 (-40) = 169 x = (3 169) 2 = (3 13) 2x = 5 or -8

Please refer to the following for details:

x3x-40 = 0 directly substituting the Yan Yan into the Siyanyu formula:

x 2 3x-40 = 0 delta = 3 2-4 1 (-40) = 169 x = (3 169) 2 = (3 13) 2x = 5 or -8

With Xiang Bei root axbx c = 0, root x = b b-4ac)) 2a) Here substituting a = 4, b = -6, c = 0 into the above equation gives x = 6 (-6)) 8, i.e. x1 = 6-6) 8 = 0x2 = (

x y = ln(xy), method 1, both sides of x derive, note that y is a function of x, get.

y-xy')/y^2 = y+xy')/xy), x(y-xy') y(y+xy'), get dy dx = y'=xy-y 2) mill (x 2+xy) =y x) (x-y) (x+y).

Method 2, x y = ln(xy), i.e. x = yln(xy), and f = yln(xy) -x

f'x = y[y/(xy)] 1 = y/x - 1, f'y = ln(xy) +y[x/(xy)] x/y + 1

dy/dx = f'x/f'y = 1-y x) (x y+1) =y x)(x-y) blind answer (x+y).

When the goods arrive, check to see if they have been opened to prevent them from being mixed into empty bottles. It has already been discovered.

Refrigeration coefficient formula.

wc=t2/(t1-t2）

Note that the Kelvin temperature is used to calculate (Kelvin = Celsius + 273) t2 = -18 + 273 = 255k

t1=28+273=301k

wc=t2/(t1-t2）=255/(301-255）=

(1)：1/6

Two rolls, there are 36 combinations, and their probability is the same, and there are 5 combinations that sum 6, which are: 15, 24, 33, 42, 51.