Chất tinh khiết là:

A. Có tính chất thay đổi

B. Có lẫn thêm vài chất khác

C. Gồm những phân tử đồng dạng

D. Không lẫn tạp chất

Answers

Answer 1

Answer:

The FitnessGram™ Pacer Test is a multistage aerobic capacity test that progressively gets more difficult as it continues. The 20 meter pacer test will begin in 30 seconds. Line up at the start. The running speed starts slowly, but gets faster each minute after you hear this signal. [beep] A single lap should be completed each time you hear this sound. [ding] Remember to run in a straight line, and run as long as possible. The second time you fail to complete a lap before the sound, your test is over.

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Related Questions

the text of oxygen gas in the laboratory ​

Answers

Explanation:in testing for oxygen a glowing splint is used.

the glowing splint is brought in the presence of the test tube containing the gas

the glowing splint rekindles or lights up showing that oxygen is present.

this is a positive test because oxygen supports burning or combustion

Please help me with my work

Answers

D. 2

Explanation:

To be balanced, the hydrogen and chlorine atoms are both 2 and 2 in the products side. Hence, we must add a two to the HCl in order to have 2 hydrogens and 2 chlorines in the reactants.

Hope this helps, brainliest would be appreciated :)

Answer:

2

Explanation:

There's 2 Hydrogen and Chlorine molecules on the right side with one Zinc. So the left side needs to have a coefficient of 2 on the hydrochloric acid, or HCl.

Describe weighted average

Answers

Answer:

Explained below

Explanation:

In simple average, we just add all the given data variables and divide it by the number of data given.

However, when it comes to weighted average, what we do is that we multiply each given variable by their weights and then divide the sum of that by the sum of the weights.

Thus, if the variables are denoted by x and their weights are denoted by y, then we have;

Weighted average = Σ(xy)/Σy

Suppose that three isotopes of element X occur in nature as follows:

The relative atomic mass of the naturally occurring mixture of element X is

Answers

Answer:

107.5 amu

Explanation:

isotopes:                                                                     fractional      Wt Avg

           isotopes: isotopic mass   %Abundance      abundance      (amu)    

              X110              110                          60                0.60            66.0

             X105              105                         30                0.30             31.5

             X100              100                         10                 0.10             10.0

                                                      ∑ atm mass contributions      =    107.5 amu*

*amu = atomic mass units

What happens to a glass of sugar solution when sugar is added to it?

The number of moles of water increases.
The number of moles of water decreases.
The molarity of the solution increases.
The molarity of the solution decreases.

Answers

When sugar is added to a glass of sugar solution, the molarity of the solution increases. Details about molarity can be found below, which is the third option.

What is molarity?

Molarity is a term used to identify the amount of solute, in moles, dissolved in a solvent by volume. Molarity is expressed as moles per liter (mol/L).

However, molarity is directly proportional to the amount of solute in solution. This means that as the amount of solute increases, molarity also increases.

Therefore, when sugar is added to a glass of sugar solution, the molarity of the solution increases.

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What is the difference between an exothermic and an endothermic reaction?

A. Endothermic reactions absorb heat.

B. Exothermic reactions absorb heat.

C. There are no changes in heat during either reaction.

D. Endothermic reactions release heat.

Answers

answer D

Explanation:hope thhis helped

High-pressure liquid chromatography (HPLC) is a method used in chemistry and biochemistry to
purify chemical substances. The pressures used in this procedure range from around 500
kilopascals (500,000 Pa) to about 60,000 kPa (60,000,000 Pa). It is often convenient to know
the pressure in torr. If an HPLC procedure is running at a pressure of 3.20x10^8 Pa , what is its
running pressure in torr?
Express the pressure numerically in torr.

3.20 x 10^8 Pa = _____ torr

Answers

Answer:

2,400,000 torr (3 s.f.)

Explanation:

Convert the pressure from Pascal to atm first:

[tex]\boxed{1 \: atm = 101325 \:Pa }[/tex]

3.20 ×10⁸ Pa

= [(3.20 ×10⁸) ÷101325] atm

= 3158.2 atm (5 s.f.)

Convert atm to torr:

[tex]\boxed{1 \: atm = 760 \: torr}[/tex]

3158.2 atm

= (3158.2 ×760) torr

= 2400000 torr (3 s.f.)

- calculate relative formula mass
[N=14, O=16, Mg=24, Al=27]

1) Mg(NO3)2

- calculate relative molecular mass
[H=1, C=12, O=16]

1) C4H10

2) CH3COOH​

Answers

Mg(NO3)2:-

[tex] \\ \sf \longmapsto \: 24u+2(14u+3\times 16u)[/tex]

[tex] \\ \sf \longmapsto \: 24u+2(14u+48u)[/tex]

[tex]\\ \sf \longmapsto \: 24u+2(62u)[/tex]

[tex] \\ \sf \longmapsto \: 24u+(124u)[/tex]

[tex] \\ \sf \longmapsto \: 148u[/tex]

please help with the attached picture question 21, 22, 23

Answers

Explanation:

21. The given molecule for cracking is tetradecane.

On cracking it forms one mole of decane (C10H22) and two moles of ethene gas.

The chemical equation is shown below:

[tex]C_1_4H_3_0->C_1_0H_2_2+2C_2H_4[/tex]

22. The essential condition for the formation of an ester is the reaction of alcohol and acid in presence of concentrated sulfuric acid.

Thus among the given options, the first option is the correct one.

23. Isomers of butanol are shown below:

It is 2-butanol.

The position of -OH group changes to the second carbon.

PLZ HELP Question 2 of 25 What is the total number of atoms in the molecule CzHg?
A. 2
B. 8
C. 11
D. 3​

Answers

A. 2

One Cs (Caesium), the other one Hg (Mercury)

Note: we don't have Cz this might be Cs

Determine the mass of 6.33 mol of iron(II) nitrate.

Answers

Answer:

1822.72 g

Explanation:

Applying,

n = R.M/M.M.................. Equation 1

Where n = number of moles of iron(II) nitrate, R.M = Reacting mass of iron(II) nitrate, M.M = molar mass of Iron(II) nitrate.

Make R.M the subject of the equation

R.M = n×M.M............. Equation 2

From the question,

Given: n = 6.33 mol

Constant: M.M of iron(II) nitrate = 287.95 g/mol

Substitute these values into equation 2

R.M = 6.33(287.95)

R.M = 1822.72 g

Hence the mass of iron(II) nitrate is 1822.72 g

You work in the special effects department of a movie studio. You are currently working on a superhero movie where the hero is very strong and cannot be hurt by normal weapons such as a sword. In the next scene, the villain is going to hit the hero with a lead pipe. The hero's costume is mostly made of foam and carbon so that is it very light and easy to move around in but will crumble if hit with anything hard. For this scene, a section of the costume needs to be replaced with a different material that will only dent, not crumble, when hit with the pipe. You are on a deadline and look around the props department for ideas, what could you use?

Answers

Answer:

Aluminum or Galvanized iron

Explanation:

If the costume has to be such that the hero does not get hurt when hit by a lead rod and also is easy for the mobility then the suitable option for the costume could be Aluminum material which will only dent and not crumble.

Galvanized iron could be another choice being harder and stronger as compared to aluminum but a little heavy. It can sustain heavy impacts as compared to aluminum.

Answer:

You could use a shield if you are not speaking from a scientific way.

Which of the following elements is the smallest?

Answers

Explanation:

where is options?????????????????

Helium is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements. Wikipedia
Symbol: He
Atomic mass: 4.002602 u
Atomic number: 2
Electron configuration: 1s2
Electrons per shell: 2
Boiling point: -268.9 °C

what do you mean by 1 joule work​

Answers

Answer:

Joule is the SI unit of work. 1 Joule is amount of work done when a force of 1 Newton displaces a body through a distance of 1m in the direction of the force applied.

Specific heat capacity is _____.


greater for metal than for wood

the amount of heat required to raise the temperature of 1g of a substance 1 oC

represented by the symbol, Q

all of these

Answers

Answer:

all of this

Explanation:

Which of the following is an example of a solution?

A. An iron alloy
B. Iron metal
C. Iron rust
D. An iron ore

Answers

Answer:

A: an iron alloy.

Explanation:

Because iron alloy consists of minor components that are distributed within the major component, which is the basic requirement for a solution.

Plz Help I have One more time To retake and I can't fail it..​

Answers

Answer:

B. Radar uses radio and the siren uses sound waves. both exhibit in the Doppler effect.

sorry if this is wrong

What is the boiling point of water?​

Answers

Answer:

212°F , 100°C , 373.15°K

They are all the same, in different units.

Answer:

The boiling point of water is 212 degrees fahrenheit, and/or 100 degrees celsius.

Re-word this statement: Ionic Radii are changing as you move down the column because the atoms in lower rows have more energy levels, which makes the valence electrons farther from the nucleus, so it takes less energy for them to be pulled away.
The Ionic radii are changing as you move across a row because each element has one more proton, which increases the attraction of the nucleus.

Answers

Answer:

ty po hehe

Explanation:

mark me as brainliest po thank you

How much water will the measuring cup have if you poured 1/2 of it out?

Answers

The cup will be filled up halfway

5. The energy diagram shown illustrates a reaction which is
an
A. exothermic reaction.
B. activated complex.
C. equilibrium reaction.
D. endothermic reaction.

Answers

Answer:

Explanation:

The answer is an exothermic reaction so A.

Fe2O3 +3CO--2Fe+3CO2 .identify the substance oxidized ,reduced and oxidizing agent and reducing agent​

Answers

Answer:

Oxidized : CO

Reduced: Fe

Oxidizing agent: Fe2O3

Reducing agent: CO

Explanation:

Loss of electrons is oxidation while gaining of electrons is reduction.

CO is a reducing agent, Fe2O3 is an oxidizing agent.

Each carbon atom is oxidized in CO. CO is the reducing agent

Each Fe atom in FeO3 is reduced. FeO3 is the oxidizing agent

which of the following is a physical change? 1.burning paper 2.grinding wheat 3.electrolysis of water 4.cooking rice​

Answers

Answer:

2 grinding of wheat is just a physical change

plz brainlist

How is a slump different from creep?

Answers

Answer:

Is this chemistry or ELA!

its not a question but i wanted to tell you guys that if you guyz like my answers then please don't forget to give like and follow at the same time. I am not forcing you to follow only if you guyz like my answer then like or follow. THANKS FOR READING..​

Answers

Answer:

thank you for this oibnki

Answer:

Sure I'll go ahead and like your answers and follow you if that's what you wanted! :)

Explanation:

Which of the following is not a pure form of a substance ?

A.Element
B.Atom
C.Molecule
D.Mixture
E.Compound

Answers

Answer:

Which of the following is not a pure form of a substance ?

C.mixture

Explanation:

since mixture is created due to one or more than two element,compound,molecule or atom.

Answer:

option D . mixture.

Explanation:

Mixture is not a pure form of a substance .

it is formed when two particles mixed together in one substance

Hope it is helpful to you ❣️✌️☺️☪️❣️

Select the structure corresponding to trans-3-octene.

Answers

Answer: B

Explanation:

Answer:

The Correct Answer Is B.

. De las siguientes soluciones:

1. 20 ml de alcohol etílico mezcladas con 80 ml de agua.

2. 500 ml de agua con 20 g de sal disueltas (V Sln: 500ml).

3. 80 g de sal en 2 litros de agua.

a) Identifica el soluto y solvente de cada solución y explica ¿por qué?

b) Encuentra la concentración por peso de la solución número 3 c) Entre la disolución 2 y 3 ¿Cuál presenta mayor concentración?

por favor lo necesito para hoy ¡gracias!

Answers

Answer:

can u translate this to English? I might be able to help

a) Solution 1: Solute is ethyl alcohol, solvent is water. Solution 2 and 3: Solute is salt, solvent is water.

b) Concentration by weight of solution 3: Approximately 3.85%.

c) Solution 3 has a higher concentration than solution 2.

a) Solutions and their solutes and solvents:

Solution 1: The solute is ethyl alcohol, and the solvent is water. This is because ethyl alcohol is the substance that dissolves in water to form the solution.

Solution 2: The solute is salt, and the solvent is water. Salt is the substance that dissolves in water to form the solution.

Solution 3: The solute is salt, and the solvent is water. Similar to solution 2, salt is the substance that dissolves in water to form the solution.

b) Weight concentration of solution number 3:

The weight concentration is calculated by dividing the mass of the solute (80 g of salt) by the total mass of the solution (80 g of salt + 2000 g of water):

Weight concentration = (80 g / 2080 g) * 100% ≈ 3.85%

c) Comparison of concentrations between solution 2 and 3:

Solution number 3 has a higher concentration than solution 2, as the weight concentration of solution 3 is approximately 3.85%, while the exact amount of water is not provided for solution 2 to calculate its concentration. However, solution 2 contains only 20 g of salt dissolved in 500 ml of water, which implies that the concentration will be lower than solution 3. Therefore, solution number 3 has a higher concentration compared to solution 2.

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mention two factors which affect pressure due to liquid contained in a vessel​

Answers

Answer:

depth of the liquid and nature of liquid affects the pressure due to liquid contained in a vessel

Answer:

Two factors influence the pressure of fluids. They are the depth of the fluid and its density. A fluid exerts more pressure at greater depths

How does a cirrus cloud look like
1) cotton
2) thin feather​

Answers

Answer:

2) thin feather​

Explanation:

Cirrus clouds are delicate, feathery clouds that are made mostly of ice crystals. Their wispy shape comes from wind currents which twist and spread the ice crystals into strands.

hope it helps :)

please mark brainliest!!!

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