(sulfuric acid 500ml, relative molecular weight: 98, density: 1.84g/cm3, mass fraction: 0.98) Solution: the mass of sulfuric acid solution in the reagent bottle is? G &#To prepare 200 grams of 20% dilute sulfuric acid, how many grams of the solution? How many milliliters?  

(sulfuric acid 500ml, relative molecular weight: 98, density: 1.84g/cm3, mass fraction: 0.98) Solution: the mass of sulfuric acid solution in the reagent bottle is? G &#To prepare 200 grams of 20% dilute sulfuric acid, how many grams of the solution? How many milliliters?  

Science (urgent!) (26 19:51:55)
Potassium, calcium and sodium can't replace metals from salt solution, because they will react first. So why is it OK in acid solution?

Even if it reacts with water to form alkali and hydrogen. Alkali reacts with acid in solution to form salt and water. So the general equation is metal + acid = = Salt + hydrogen

A small car needs 325 liters of gasoline to travel 32 kilometers, and how many liters of gasoline to travel 1 kilometer?

325 △ 32 = 225 (liter); a: it takes 225 liters of gasoline to travel 1 kilometer

Given that the point P (sin α + cos α, Tan α) is in the second quadrant, the value range of angle α is______ ．

∵ point P (sin α + cos α, Tan α) is in the second quadrant, where ∵ sin α + cos α < 0 and Tan α > 0 are known by sin α + cos α < 0, the terminal edge of α is below the bisector of the second and fourth quadrants, known by Tan α > 0, and the terminal edge of α is in the first and third quadrants, so that the common area is the third quadrant in the coordinate system, and the value range of ∵ angle α is (2k π + π, 2K π + 3 π 2) k ∈ Z

There is a batch of cement on the construction site. 40 tons of cement are transported in the first day and 41 tons in the second day. The mass ratio of the remaining cement to the transported cement is 4:3
How many tons of this batch of cement?

This batch of cement workers is set at x tons
Then (x-40-41) / (40 + 41) = 4 / 3
(x-81)/81=4/3
3x-243=324
3x=567
x=189
So there are 189 tons of cement in this batch

If the length of three sides of a triangle is a continuous natural number, and its perimeter m satisfies 10 "m" 22, then how fast is the triangle angle

4
{(3,4,5),(4,5,6),(5,6,7),(6,7,8)}

There are 6 tons of cement, stone and sand respectively. Concrete is made by mixing cement and stone and sand in the ratio of 5:3:2. If the stone is just used up, how many tons of cement are missing? How many tons more yellow sand?

Lack of cement 6 × 53-6, = 10-6, = 4 (tons), more yellow sand 6-6 × 23, = 6-4, = 2 (tons). Answer: lack of cement 4 tons, more yellow sand 2 tons

Given that the function y = f (x) is an even function and y = f (X-2) is a monotone decreasing function on [0,2], then ()
A. f（0）＜f（-1）＜f（2）B. f（-1）＜f（0）＜f（2）C. f（-1）＜f（2）＜f（0）D. f（2）＜f（-1）＜f（0）

Let y = f (X-2) monotonically decrease on [0,2] and ∵ y = f (x) monotonically decrease on [- 2,0]. ∵ y = f (x) is an even function and ∵ y = f (x) monotonically increase on [0,2]. In addition, f (- 1) = f (1), so we choose a

There are three workshops in a factory. The ratio of the number of people in the first workshop to that in the second workshop is 3:2. The number of people in the third workshop accounts for 1 / 3 of the total number of workers in the whole factory, which is known as the first workshop
It is known that there are 80 more people in the first workshop than in the second workshop. How many people are there in this factory?

80x(3+2)/(1-1/3)
=400/(2/3)
=600 people

If x, y ∈ R + and X3 + Y4 = 1, then the maximum value of XY is 0______ ．

Because x ＞ 0, y ＞ 0, so 1 = X3 + Y4 ≥ 2 & nbsp; x3y4 ≥ XY3 (if and only if X3 = Y4, that is, x = 32, y = 2, take the equal sign), then XY3 ≤ 1, XY ≤ 3