NEED HELP! An experiment _____. must always be done in a laboratory is best done if only one variable is tested for at a time can be done only by direct observation must always be done in the field

Answers

Answer 1

Answer:

Chemically

in chemistry


Related Questions

whats the chemical formula for dilute hydroxide acid​

Answers

the chemical formula is OH −

Explain Redox tiltration and examples of half - life reactions.​

Answers

Answer:

Explanation:

Half life reactions take place in electrochemistry where u have to find the emf generated from a cell

E.g Mg(s)/Mg(aq)//Ag(aq)/Ag(s)

Can Chlorine be harmful to any of the earth’s ecosystems? If so how?

Answers

Answer:

Although chlorine itself usually does not cause environmental harm, it combines rapidly to form chemicals such as dioxins that pollute water, contaminate fish and transfer to humans and larger animals that eat the fish.

Explanation:

Which element is needed for
a. Bone and teeth formation.
b. Treatment of water.

Answers

Bone and teeth formation
Treatment of water

Answer:

a.calcium

b.chlorine

Another chemistry question. Help me!
To prepare 250cm³ of standard solution of 1.0 mol dm-³ sodim carbonate Na2Co3​

Answers

Answer:

Molar mass Na2CO3 = 2*23 + 12 + 3*16 = 106 g/ mol

Mass of 1 mol Na2CO3 = 106 g

mass (Na2CO3) = 106g*250cm³/1000cm³ = 26.5 g

1) It is necessary because all Na2CO3 will be in the solution, and no Na2CO3 would be lost.

2) Because the solution that was formed after rinsing beaker contains Na2CO3.

3) Eyes should be on the level of calibration mark of the volumetric flask.

4) It is necessary to prevent evaporation of water, and changing , because of it, the concentration of the solution.

Which of the following best describes why a cruise ship floats?
A. It displaces an equal or greater amount of water than its own
weight.
B. It displaces more than half of its weight in water.
C. Its volume and mass are equal.
D. Its volume is greater than its mass.

Answers

Answer:

A. It displaces an equal or greater amount of water than its own weight.

Explanation:

Cu+2AgNO

3



→2Ag+Cu(NO

3



)

2



start text, C, u, end text, plus, 2, start text, A, g, N, O, end text, start subscript, 3, end subscript, right arrow, 2, start text, A, g, end text, plus, start text, C, u, left parenthesis, N, O, end text, start subscript, 3, end subscript, start text, right parenthesis, end text, start subscript, 2, end subscript

How many grams of \text{Ag}Agstart text, A, g, end text will be produced from 19.0 \text{ g}19.0 g19, point, 0, start text, space, g, end text of \text{Cu}Custart text, C, u, end text and 125 \text{ g}125 g125, start text, space, g, end text of \text{AgNO}_3AgNO

3



start text, A, g, N, O, end text, start subscript, 3, end subscript?

Answers

Answer:

Mass of Ag produced = 64.6 g

Note: the question is, how many grams of Ag is produced from 19.0 g of Cu and 125 g of AgNO3

Explanation:

Equation of the reaction:

Cu + 2AgNO3 ---> 2Ag + Cu(NO3)2

From the equation above, 1 mole of Cu reacts with 2 moles of AgNO3 to produce 2 moles of Ag and 1 mole of Cu(NO3)2.

Molar mass of the reactants and products are; Cu = 63.5 g/mol, Ag = 108 g/mol, AgNO3 = 170 g/mol, Cu(NO3)2 = 187.5 g/mol

To determine, the limiting reactant;

63.5 g of Cu reacts with 170 * 2 g of AgNO3,

19 g of Cu will react with (340 * 19)/63.5 g of AgNO3 =101.7 g of AgNO3.

Since there are 125 g of AgNO3 available for reaction, it is in excess and Cu is the limiting reactant.

63.5 g of Cu reacts to produce 108 * 2 g of Ag,

19 g of Cu will react to produce (216 * 19)/63.5 g of Ag = 64.6 g of Ag.

Therefore mass of Ag produced = 64.6g

84. A salution of a substance x is used
of a
for
il Name the sulsstance 'x' and the
white kashing
write its farmula
il y Write the reaction the substance
la' named in il above with water.
of
dne

Answers

Answer:

Following are the answer to this question:

Explanation:

(1) Calcium oxide (CaO) is also referred to as quicklime. It is the solution for the substance used for whitewashing.  

Whenever it reacts with water ([tex]H_2O[/tex]) and absorbs carbon dioxide ([tex]CO_2[/tex]), it then formed calcium carbonate ([tex]CaCO_3[/tex]), which produced a hard laminate on the walls, to first be whitened by the production of calcium hydroxide (CaOH).  

(2) Slackened lime or calcium hydroxide arises whenever the fast limestone reacts with water.

[tex]CaO(s) + H_2O(l) \rightarrow Ca(OH)_2(aq).[/tex]

Another name for a statovolcano is a _____ volcano because it is made of alternating layers of thick, sticky lava and volcanic rock and ash. A. shield B. cinder C. composite D. pyroclastic

Answers

Answer:

Bcinder

Explanation:

PLS HELP ! 5.00 mL of a stock solution, containing 0.200 M of Na3PO4 was pipetted into a 25.00 mL volumetric flask and made up to the calibration mark with deionised water. A serial dilution was carried out for another two times to obtain the final solution of desired concentration. Calculate the concentration of the final solution, express in ppm (by volume).

Answers

Answer:

262 ppm of Na₃PO₄

Explanation:

In a dilution, the concentration of the initial solution is decreased. When you take 5.00mL of the solution that is diluted to 25.0mL The solution is diluted 25/5 = 5 times

If you make another two serial dilutions the final solution wil decrease its concentration 5*5*5 = 125 times

As original solution containing 0.200 M of Na3PO4, the final solution will have a concentration of:

0.200M / 125 = 1.6x10⁻³M

Molarity is defined as the ratio between moles and liters. 1.6x10⁻³ moles of Na3PO4 in 1L are:

1.6x10⁻³mol ₓ (164g/mol) = 0.262g Na₃PO₄ / L

Assuming density of Na3PO4 as 1g/mL the concentration of the solution is:

0.262mL Na₃PO₄ / L

As 1mL = 1000μL:

262μL Na₃PO₄ / L

μL of solute per L of solution is equal to ppm, that means the solution has:

262 ppm of Na₃PO₄

can periodic table indicates occurrance of the elements, why?​

Answers

Answer: No

Explanation:

A periodic table can be defined as the table in which the row of chemical elements are present. All the elements of the row have same number of electron shells.

The arrangement of elements is based on atomic numbers, electron shell model and other chemical properties. The elements are placed in increasing order of atomic number.

This table does not give information about the occurrence of the elements.

2 Points
A student blows a whistle. In which direction do the air particles vibrate with
respect to the direction the sound wave travels?

A. Perpendicular to

B. Parallel to

C. At a 45 degree angel to

D. At an unpredictable angel

Answers

Answer:

parallel to

Explanation:

In parallel direction the air particles vibrate with respect to the direction the sound wave travels. The correct option is B.

What is sound wave?

A sound wave is the pattern of disturbance caused by the movement of energy as it propagates away from the source of the sound through a medium (such as air, water, or any other liquid or solid matter).

Sound waves are produced by object vibrations and pressure waves, such as a ringing cellphone.

Because sound waves are produced by compressions and rarefactions in the air, they are referred to as longitudinal waves. The air particles vibrate in a direction parallel to the propagation direction.

The particles in a longitudinal wave are displaced parallel to the direction of the wave. Compressions moving along a slinky are an example of longitudinal waves.

Air particles vibrate in a parallel direction to the direction of travel of the sound wave.

Thus, the correct option is B.

For more details regarding sound waves, visit:

https://brainly.com/question/21995826

#SPJ2

Jaiden is writing a report about the structure of the atom. In her report, she says that the atom has three main parts and two subatomic particles. Do you agree with her? Why or why not?

Answers

Answer:

The smallest constituent of an element is termed as an atom. According to Jaiden, an atom comprises two subatomic particles and three prime parts, however, this is incorrect as an atom comprises three subatomic particles and two main parts. The three subatomic particles are the protons, electrons, and neutrons. All these parts are smaller in comparison to an atom, thus, they are considered as subatomic particles.  

To be considered as an atom, an atom is needed only electrons and neutrons, like hydrogen exhibit one electron and one proton. On the other hand, the overall charge of the atom is not affected by the presence of neutrons, it is the subatomic particle that only enhances the mass of the atom.  

Answer:

I disagree with her because an atom has two main parts: the nucleus and the electron cloud. Atoms have three subatomic particles: protons, neutrons, and electrons.

Explanation:

How many grams of H2S is needed to produce 18.00g of PbS if the H2S is reacted with an
excess (unlimited) supply of Pb(CH3COO)2?

Answers

Answer:

2.56 grams of H₂S is needed to produce 18.00g of PbS if the H2S is reacted with an  excess (unlimited) supply of Pb(CH₃COO)₂

Explanation:

The balanced reaction is:

Pb(CH₃COO)₂ + H₂S → 2 CH₃COOH + PbS

By stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction) they react and produce:

Pb(CH₃COO)₂: 1 moleH₂S: 1 moleCH₃COOH: 2 molesPbS: 1 mole

In this case,  to know how many grams of H₂S are needed to produce 18.00 g of PbS, it is first necessary to know the molar mass of the compounds H₂S and PbS and then to know how much it reacts by stoichiometry. Being:

H: 1 g/moleS: 32 g/molePb: 207 g/mole

The molar mass of the compounds are:

H₂S: 2* 1 g/mole + 32 g/mole= 34 g/molePbS: 207 g/mole + 32 g/mole= 239 g/mole

So, by stoichiometry they react and are produced:

H₂S: 1 mole* 34 g/mole= 34 gPbS: 1 mole* 239 g/mole=   239 g

Then the following rule of three can be applied: if 239 grams of PbS are produced by stoichiometry from 34 grams of H₂S, 18 grams of PbS from how much mass of H₂S is produced?

[tex]mass of H_{2} S=\frac{18 grams of PbS*34 grams of H_{2}S }{239 grams of PbS}[/tex]

mass of H₂S= 2.56 grams

2.56 grams of H₂S is needed to produce 18.00g of PbS if the H2S is reacted with an  excess (unlimited) supply of Pb(CH₃COO)₂

Calculate the molar mass of CH4 gas at STP when 5.46Lof the gas weighs 4g??​

Answers

Answer:

About 16.42 grams

Explanation:

[tex]PV=nRT \\\\(1)(5.46L)=n(0.0821)(273) \\\\n\approx 0.2436 \\\\4g/0.2436\approx 16.42[/tex]

Hope this helps!

What does "A" represent in a the standard form of a double replacement reaction? a.) otion b.) cation

Answers

Answer: cation

Explanation:

"A" represent in a cation in the standard form of a double replacement reaction. Therefore, option B is correct.

What is cation ?

Positively charged ions are known as cations. Negatively charged ions are known as anions. Ions are positively or negatively charged atoms or molecules. A balanced atom will become a positively charged cation if one or more electrons are lost.

In an electrical field, these ions are known as "cations" because they are positively charged and migrate toward the negative electrode (cathode).

The double-replacement reaction generally take up the form of AB + CD → AD + CB where A and C are positively-charged cations and B and D are negatively-charged anions.

Thus, option B is correct.

To learn more about the cation, follow the link;

https://brainly.com/question/28710898

#SPJ6

if the balloon is 67,000 L at STP, what volume would it be if the air temperature cool to10.0°C in the pressure dropped to 99.2kPa as the balloon went higher?

Answers

Answer: The volume is 70872 L

Explanation:

Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.

The combined gas equation is,

[tex]\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]

where,

[tex]P_1[/tex] = initial pressure of gas (STP) = 1 atm

[tex]P_2[/tex] = final pressure of gas = 99.2 kPa = 0.98 atm  (1kPa=0.0098atm)

[tex]V_1[/tex] = initial volume of gas  = 67000 L

[tex]V_2[/tex] = final volume of gas = ?

[tex]T_1[/tex] = initial temperature of gas (STP)  = 273K

[tex]T_2[/tex] = final temperature of gas = [tex]10.0^0C=(273+10)K=283K[/tex]

Now put all the given values in the above equation, we get:

[tex]\frac{1\times 67000}{273}=\frac{0.98\times V_2}{283}[/tex]

[tex]V_2=70872L[/tex]

Thus the volume is 70872 L

Which of these observations are not explained by kinetic-molecular theory?

Answers

The question's incomplete unfortunately, which observations?

Answer:

At very low temperatures, gases expand less for a given pressure change than they do at high temperatures

URGENT!!!!
An ordered list of chemical substances is shown.

Which substances in the list can be some of the reactants and products in the same combustion reaction? (4 points)

Select one:
a. 1, 2, and 3
b. 2, 3, and 6
c. 1, 4, and 5
d. 1, 2, and 5

Answers

Answer : The correct option is (b) 2, 3, and 6

Explanation :

Combustion reactions: It is defined as the reactions in which a hydrocarbon reacts with oxygen gas to produce carbon dioxide and water.

A balanced chemical equation is defined as the equation in which total number of individual atoms on the reactant side is equal to the total number of individual atoms on product side.

The general chemical equation for the combustion is as follows:

[tex]C_xH_yO_z+O_2\rightarrow CO_2+H_2O[/tex]

where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.

The reactants and products in the same combustion reaction are [tex]O_2[/tex] and [tex]CO_2,H_2O[/tex] respectively.

Hence, the correct option is (b) 2, 3, and 6

What is Charles’s law? State the definition of the law in words. What are the assumptions of Charles’s law? Write mathematical equations that represent the law. What can you do with Charles’s law? Using a gas-filled balloon as an example, describe what happens to the gas molecules that behave according to Charles’s law.

Answers

Answer:

The volume of a given mas of a gas is directly proportional to the temperature if the pressure remains constant

V is directly proportional to T

V=1/T

V=constant/T

Explanation:

Charles law states that the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature, if the pressure remains constant.

e.g., In winters as the temperature falls off, when you take a basketball outside in the ground the ball shrinks.

The mathematical equation that represents Charles law:

V₁/T₁ = V₂/T₂

where, V₁ = initial volume

T₁ = initial absolute temperature

V₂ = final volume

T₂ = final absolute temperature

The applications of Charles law has in daily life are:

Helium balloons shrinks in a cold weather.The capacity of the human lung decreases in winter season. This makes difficult for the athletes to perform in winter season and it also makes it difficult for people to go jogging.

A gas-filled balloon experiment:

If a balloon is filled with air, it will shrink when cooled and the balloon expands if heated. This happens because the air inside the balloon, which is a gas molecules, occupies a smaller volume when it is cool, and occupies  a larger volume when it is hot.

To learn more about Charles law here

https://brainly.com/question/16927784

#SPJ2

Name two drying agents that can be use to dry hydrogen gas​

Answers

CaCl2, Na2SO4, MgSO4 are three drying agents that can be used to dry hydrogen gas

If 119.5 g of iron is mixed with 279.50 g of copper (II) nitrate, what is the limiting reagent for the reaction?

Answers

Answer:

Copper ii nitrate is the limiting reagent

Explanation:

The first thing to write here is the equation of reaction;

Fe + Cu(NO3)2 ——> Fe(NO3)2 + Cu

When we talk of limiting reagent, we mean the reactant that is totally consumed upon the completion of the chemical reaction

To get the limiting reagent, we can know this by calculating the mass of a specific product formed from each of the masses of the reactants

Now, we can use the amount of copper solid deposited by each of the reactants to know the limiting reagent here.

Since the mole ratio in all cases is 1 to 1, this will be easy

For the iron, the number of moles reacted is mass of iron/ atomic mass of iron

That would be 119.5/56 = 2.134 moles

Now since the mole ratio is 1 to 1, 2.134 moles of copper will be formed

Thus, the mass of copper produced from the iron will be number of moles * atomic mass of copper = 2.134 * 64 = 136.57g

Now from the nitrate, the number of moles is

mass mixed/ molar mass of copper nitrate

molar mass of copper nitrate is 188g/mol

number of moles is thus 279.5/188 = 1.487 moles

Since the mole ratio is 1 to 1, it means that the number of moles of copper produced too is 1.487 moles

The mass of copper produced from this is number of moles of copper * atomic mass of copper

That will be 1.487 * 64 = 95.15g

Now, since the copper nitrate produces less amount of copper solid, it is the the reagent to be consumed first and thus it is our limiting reagent

Other Questions
what is the term for skills that historians apply to analyze evidence in order to make meaning of the past The diameter of a sphere is 2 ft. What is the sphere's volume? Round to the nearest tenth.A)4.2 ft3B)8.1 ft3C)16.8 ft3D)33.5 ft3 The free-market system cannot exist without government regulation for whatreason?O A. The profit motive undermines competition unless competition isprotectedB. Theft, coercion, and fraud are fundamental features of a free-market economy.C. Collective bargaining agreements always favor workers over theiremployers.D. There are various definitions of freedom, equality, security, andgrowth Which of the following describes a difference between france just after the French Revolution and after Napoleon. A. Just after the revolution, France was divided into three estates after Napoleon rose to power, he abolished all estates. B. Just after the revolution, France has a representative form of government. After Napoleon rose to power, he became emperor.C. Just after the revolution, France has a capitalist economy. After Napoleon rose to power, he reinstituted the feudal System.D. Just after the revolution, France practiced religious tolerance. After Napoleon rose to power, he required that all french people become Catholics Unit TestActiveTIME REMAINING1201:55:24Which statement best describes the direction of heat flow by conduction between two samples of the same material?Heat flows from faster molecules to slower molecules when they are near.Heat flows from faster molecules to slower molecules when they collide.Heat flows from slower molecules to faster molecules when they are near.Heat flows from slower molecules to faster molecules when they collide. What is the coordinate of point P that lies along the directed line segment from Q(2,5) to R7, 12) and partitions the segment in the ratio of 3 to 2?Your answer.0 (3, 42)O(4.5, 8.5)O (5,9.2)O (5,7)Clear answer What is 13 out of 25 as a decimal? Plzzz help Peter Smith, a 73 years old male with mild type II diabetes, calls to schedule an appointment. He states that he is feeling very anxious and fatigued and is having difficulty eating and sleeping Match the verb to the correct affirmative t command.venir tener poner salir hacer decir ir ser sacar jugar Anna has to present color concepts to her class. Help her complete the following sentences.When you add white to a hue, its value increases, and you get differentand you get different _____of that hue.of that hue. When you add black to a hue, its value decreases and you get different ____ of that hue. in what ways did the populist movement make a lasting impact? Ecosystems are closed environments.TRUEFALSE How does a male get circumcised? For the parallelogram ABCD the extensions of the angle bisectors AG and BH intersect at point P. Find the area of the parallelogram, if DG = GH, AB = 39 in, GP = 12 in. WILL MARK BRAINLIEST AND 20 POINTS!!!!Iguanas need to live in a habitat that is very warm, so the pet store warms their enclosures with basking lights which act as an artificial sun. Describe how the three methods of thermal energy transfer may take place within the iguanas enclosure. Which sentence most clearly uses an ethos appeal?A. The look on this poor child's face is the only reason you need todonate todayB. If you buy our stock now, you can double your money before theyear is out.C. As a professor of ancient history, I know a thing or two aboutclassical Greece.D. All of you should feel ashamed for not doing anything about crimein America. PracticeRead the follozing debate topics, fren make up four or five of your own. Notethat the statements are written in the affirmative rather than the negative. Forinstaaz, "Smoking should be banned in resizaranis rather than people shoulanot be allowed to smoke in restaurants." 4.The US Senate rejected the Treaty of Versailles partly because they did not want to(A) pay reparations.(B) join the League of Nations.(C) force Germany to pay reparations.(D) be allied with Great Britain.please help thank youuuu! uses of gene cloning in the production of human insulin List three facts about glucose.