What is the cause of change over time in a population?
O The environment modifies.
O All members can mate easily with all other members.
O No new members come in or go out.

1. D

2. C

3. E

4. B

5. A

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The molality is 0.54 M when 1.34 moles of NaCl is present in 2.47 kg of solvent.

Explanation:

Molality is the measure of how much of amount of solute is dissolved in the solvent. So it is calculated as the ratio of moles of solute to the grams of solvent.

         [tex]\text {Molality}=\frac{\text {Moles of solute}}{\text {Mass of solvent}}[/tex]

As in this case, the solute is NaCl and solvent is unknown. So the moles of solute is given as 1.34 moles and the mass of solvent is given as 2.47 kg.

Hence, [tex]\text { molality }=\frac{1.34}{2.47}= 0.54 \mathrm{M}[/tex]

Thus, the molality is 0.54 M when 1.34 moles of NaCl is present in 2.47 kg of solvent.

The molality of a solution containing 1.34 moles of NaCl in 2.47 kg of solvent is calculated by dividing the moles of NaCl by the kilograms of solvent, resulting in approximately 0.5425 moles per kilogram.

The molality of a solution is defined as the number of moles of solute per kilogram of solvent. In this case, we are asked to calculate the molality of a solution containing 1.34 moles of NaCl dissolved in 2.47 kg of solvent. To find the molality, we just need to divide the moles of solute by the kilograms of solvent.

The calculation would be:

Write down the molality equation: molality (m) = moles of solute / mass of solvent in kg.

Insert the given values into the equation: m = 1.34 moles NaCl / 2.47 kg solvent.

Calculate the result: m = (1.34 moles) / (2.47 kg) = approx. 0.5425 moles/kg. This is the molality of the NaCl solution.

Answer:

SORRY

Explanation:

jcuxicicciigxicixgsory

Answer:

                     True

Explanation:

                        Hydrocarbons are classified in to Unsaturated and Saturated classes.

                    Saturated Compounds:

                                                             These are those organic compounds which has only single bonds between the carbon atoms. For example, Alkane are the saturated compounds. The Carbon atom in these compounds are Sp³ hybridized and the geometry along carbon atom is tetrahedral.

                    Unsaturated Compounds:

                                                             These are those organic compounds which has either a double bond (alkenes) or triple bonds (alkynes) between the carbon atoms. The Carbon atom in alkenes is Sp² hybridized and the geometry along carbon atom is triangular while, The Carbon atom in alkynes is Sp hybridized and the geometry along carbon atom is linear.

                     The reaction in which alkanes (saturated) compounds are converted into alkenes are called as dehydrogenation reactions while, the reactions in which the unsaturated compounds (alkene and alkyne) are converted into saturated compounds are called as hydrogenation or reduction reactions. Hence, we can conclude that the dehydrogenation of alkanes results in the formation of unsaturated compounds.

Answer:true

Explanation: alkenes has a double bond

6.7 grams of lithium chloride will be produced.

Lithium chlorate is LiClO₃ and lithium chloride is LiCl. The reaction is,

2LiClO₃ = 2LiCl +3O₂.

So here, 2 moles of lithium chlorate produces 2 moles of lithium chloride.

Or, one molecule of lithium chlorate will produce one mole of lithium chloride.

Molecular weight of lithium chlorate =[tex]6.9 + 35.5 + 16\times3[/tex] = 90.4.

So, 14.3 grams of lithium chlorate has 0.16 moles of lithium chlorate.

Thereby, moles of lithium chloride produced is 0.16 moles.

Molecular weight of lithium chloride = [tex]6.9+35.5[/tex] = 42.4 grams.

So weight of lithium chloride produced = [tex]42.4 \times 0.16[/tex] = 6.7 grams.

Thus, weight of lithium chloride produced will be 6.7 grams.

The welder will run out of Fe₂O₃ first. Even though the mass of aluminum is larger, the reaction requires twice as much of it, so Fe₂O₃ will be used up first.

To determine which reactant will run out first, you must look at the stoichiometry of the chemical reaction. The relevant reaction here is the thermite reaction, which is:

Fe₂O₃+ 2Al → 2Fe + Al₂O₃

In the balanced reaction, you can see that 1 mol of Fe₂O₃ reacts with 2 mol of Al. Calculating moles from a given mass, Fe₂O₃ has approximately 0.012 mol and Al has approximately 3.5 mol.

Therefore, even though there is more mass of Al, Fe₂O₃ will run out first because the reaction requires twice as much Al as Fe₂O₃. This condition is called a limiting reactant problem in chemistry.

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Answer:D. 1013 g O2

Explanation: solution attached:

Convert mass of glucose to moles

Do the mole ratio of glucose and oxygen gas based on the balanced equation

Convert moles of O2 to mass using its molar mass

Answer:

The correct answer is 0, 235 mol

Explanation:

We use the formula PV =nRT. The normal conditions of temperature and pressure are 273K and 1 atm, we use the gas constant = 0, 082 l atm / K mol:

1 atm x 5, 25l = n  x 0, 082 l atm / K mol x 273 K

n= 1 atm x 5, 25l /0, 082 l atm / K mol x 273 K

n= 0, 235 mol

To calculate the number of moles of oxygen gas in 5.25 L at STP, divide the volume by the molar volume of a gas at STP, which is 22.4 L/mol. This results in approximately 0.2344 moles of oxygen gas.

The student is asking about the number of moles of oxygen gas in 5.25 liters at standard temperature and pressure (STP). To find this, we use the concept of molar volume which states that one mole of any gas at STP occupies 22.4 liters.

We can set up a conversion factor to calculate moles from volume:

Dividing 5.25 liters by 22.4 liters per mole gives us:

5.25 L / 22.4 L/mol ≈ 0.2344 moles of O2

Answer:

132

Explanation:

Answer:

132

Explanation:

Answer:

HBr + Mg(OH)2 —> MgBr2 + H2O.

To balance the above, we must do a head count of the individual atoms present to ensure they balance on both sides of the equation. To get the balance equation, add 2 in front of HBr and 2 in front of H2O as shown below:

2HBr + Mg(OH)2 —> MgBr2 + 2H2O

We can see clearly that the numbers of the individual atoms on the left side is the same on the right side

Answer:

Explanation:

If a strong acid   HA  = H=  + A-  100%

pH = -log [H+] = - log 0.1= -(-1)=1

Answer:

The pH is 1.  I got this question right on my assignment.

The mass of aluminium hydroxide is 81.12 g.

Explanation:

The chemical equation for the decomposition of Aluminium hydroxide follows:

                    2 Al(OH)3 ------> Al2O3 + 3H2O

At STP:

22.4 L of volume is occupied by 1 mole of a gas.

So, 35 L of the  volume will be occupied by = (1 / 22.4) [tex]\times[/tex] 35 = 1.56 mol

By Stoichiometry of the reaction:

3 moles of water is produced by 2 moles of Aluminium hydroxide

So, 1.56 moles of water is produced by = (2 /3) [tex]\times[/tex] 1.56 = 1.04 mol.

To calculate the mass of Aluminium hydroxide, we use the equation:

         Number of moles = given mass / molar mass

Number of moles of Aluminium hydroxide = 1.04 mol

The Molar mass of Aluminium hydroxide = 78 g/mol

Putting values in above equation, we get:

           1.04 mol = mass of Aluminium hydroxide / 78

The mass of Aluminium hydroxide needed is 81.12 grams.

Answer:

D

Explanation:

Answer:

heat is absorbed by the reaction

Explanation:

People firstly believe that the planets move in a circular orbit until Newton came up with his hypothesis by inventing calculus so that we could understood and calculated planetary orbits and their accuracy.

Explanation:

Answer:

Everyone assumed the planets were perfect circles until Newton came up with an idea. Slowly people would make maps of the orbits that added circles on circles, and they could never really explain about the movement of the planet. They simply say that planets move on circles but they lacked the math to explain or prove it. Then Newton came up with an idea of inventing calculus so that we could understood and calculated planetary orbits and their accuracy.

Firstly people used their observations and say that the orbits looked like circles, then they developed their models and did the math, and proposed their hypothesizes which were wrong, until Newton came along and tried to match a model that used elliptical orbits and invented the math that allowed him to make predictions with it. His model worked for most planets.

However he could not explain about the planet Mercury for instance since it was a very strange orbit. Then after the Einstein's theory of General Relativity he could also explain very deeply about it.

Scientists and Astronomers made hypothesizes that there was another planet orbiting too close to the sun to see with telescopes, called Vulcan, that explained mercury's orbit before Einstein's theory. Then long after we had telescopes which was good enough to see if there was a planet orbiting closer to the sun than mercury.

Answer:

An example of a capital good is "the government will open another public school in the area".

Explanation:

A capital good or complicated products and systems or (CoPS) is a reliable commodity used in the manufacturing of goods and services. These are one of three kinds of consumer commodities, while the other two are property and labor.

The three are also commonly referred to as primary production factors.They are recorded on a company's balance sheet as assets, and can be depreciated over time. Capital goods instances include furniture, buildings, machinery, equipment and fixtures.

A capital good, like a factory building or a delivery van, is a tangible asset used by an organization to produce goods or services. It is part of the production process to provide consumer goods or services.

A capital good is any tangible asset that an organization uses to produce goods or services that are used in the production process to provide consumer goods or services. Common examples of capital goods include buildings, machinery, equipment, vehicles, and tools. By this definition, a factory building would be a capital good as it is used by companies to manufacture products. Other examples include a delivery van used by a courier service or a wood oven used by a bakery.

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By combining aqueous solutions of calcium chloride and sodium carbonate, a solid calcium carbonate is produced.  The  CaCO 3  is trapped by the paper which forms as a precipitate, but the  NaCl  passes through the filter paper with the water.

Explanation:

                CaCl 2 (aq) + Na 2 CO 3 (aq) → CaCO 3 (s) + 2NaCl(aq)

Answer:

Groundwater flow rates are controlled by the permeability of the aquifer through which the water is flowing and by the local hydraulic gradient (the drop in hydraulic head per unit distance; equal to the slope of the water table for unconfined aquifers).

Explanation:

I hope that helps you

Answer:

Potential Energy

Explanation:

Right now, the match is giving off no energy to it's environment.

Light it.

Now it's giving off a few kinds:

The match has the potential to have energy, but it currently has none.

Answer:

80g

Explanation:

2H2 + O2 —> 2H2O

MM of H2O = (2x1) + 16 = 2 + 16 = 18g/mol

Mass conc. of H2O from the balanced equation = 2 x 18 = 36g

MM of O2 = 16 x 2 = 32g/mol

From the equation,

32g of O2 reacted to produce 36g of H2O.

Therefore Xg of O2 will react to produce 90g of H2O i.e

Xg of O2 = (32x90)/36 = 80g

Answer:

Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but can not usually be used to separate compounds into chemical elements or simpler compounds.[1]

Physical changes occur when objects or substances undergo a change that does not change their chemical composition. This contrasts with the concept of chemical change in which the composition of a substance changes or one or more substances combine or break up to form new substances. In general a physical change is reversible using physical means. For example, salt dissolved in water can be recovered by allowing the water to evaporate.

A physical change involves a change in physical properties. Examples of physical properties include melting, transition to a gas, change of strength, change of durability, changes to crystal form, textural change, shape, size, color, volume and density.

An example of a physical change is the process of tempering steel to form a knife blade. A steel blank is repeatedly heated and hammered which changes the hardness of the steel, its flexibility and its ability to maintain a sharp edge.

Many physical changes also involve the rearrangement of atoms most noticeably in the formation of crystals. Many chemical changes are irreversible, and many physical changes are reversible, but reversibility is not a certain criterion for classification. Although chemical changes may be recognized by an indication such as odor, color change, or production of a gas, every one of these indicators can result from physical change.

Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions.

Physical properties are characteristics of matter that can be observed or measured without changing the substance's chemical composition. Chemical properties, describe how a substance interacts with other substances, indicating its ability to undergo chemical reactions.

Physical properties are those that can be observed or measured without altering the chemical identity of a substance. These include characteristics such as color, density, melting point, boiling point, odor, and conductivity. For example, when you melt ice to form water, it remains H2O throughout the process, so the change in state (from solid to liquid) is a physical change. Similarly, the change in color of a metal when it's heated is also a physical property, as it doesn't alter the metal's composition.

Chemical properties, on the other hand, describe how a substance interacts with other substances and its ability to undergo chemical reactions. These properties include reactivity, flammability, toxicity, and the ability to rust or corrode. For instance, when iron rusts upon exposure to oxygen and moisture, it's undergoing a chemical change because its composition changes from pure iron (Fe) to iron oxide (Fe2O3).

In summary, physical properties involve observable characteristics that don't change a substance's composition, while chemical properties describe a substance's behavior in chemical reactions and how it can transform into different substances.

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Answer:

5.46

Explanation:

Answer: 5.46

Explanation:

Answer:

Heat

Explanation:

See above for the answer

nswer:

Heat

Explanation:

Heat is a form of energy (thermal energy) in transition, which is transferred by non-mechanical means due to a temperature difference.

Heat always flows from the higher temperature system to the lower temperature system.

Its nature is transitory, so it makes no sense to speak of heat stored in a system, but of heat flowing from one system or substance to another given a temperature difference.

If there is no difference in temperature, no heat will flow between systems or substances.

The coefficients in a chemical equation represent the number of molecules or formula units of the reactants and products involved in the reaction and are crucial for ensuring the conservation of mass and for stoichiometric calculations.

The coefficients in front of the reactants and products in a chemical reaction represent the relative numbers of molecules or formula units of those substances that participate in the reaction. When balancing chemical equations, these coefficients ensure that the equation adheres to the law of conservation of mass, meaning the number of atoms of each element is the same on both sides of the equation. For example, in the balanced equation for the combustion of methane, CH4 + 2O2 → CO2 + 2H2O, the coefficient '2' in front of O2 indicates that two molecules of oxygen are required for every molecule of methane (1CH4).

These coefficients also describe the mole ratio of reactants to products, which is essential for stoichiometric calculations in chemistry, enabling a quantitative assessment of the reaction. This quantification is necessary for applications such as determining the amounts of reactants needed or the amounts of products that will be formed in a given chemical reaction. Omitting a coefficient implies that the coefficient is '1', as in the molecule CO2 in the given equation.

Answer:

c

Explanation:

Answer:

c

Explanation:

Answer:

Explanation:

Q = mcAT= should be mc(T2-T1)

for Aluminum

Q = 3  1000g Al x(0.897J/gC  x(23-18 C)= 16722 J

The correct answer is 13,455

[tex]Q=mc[/tex]Δ[tex]T[/tex]

What is meant specific heat?

Specific heat, the quantity of heat required to raise the temperature of one gram of a substance by one Celsius degree.

Does Aluminium have a high specific heat?

Aluminum also has a higher specific heat capacity, it takes more energy to raise a unit mass of aluminum by one degree Celsius than iron.

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Answer:

C since however many times you repeat an experiment, it should give the exact same results or it wouldn't be accurate enough. ex if you measure a liquid to be 77ml in USA, it should give the same when measured in Germany, same with repeating experiments.

Different results from an experiment's repetition could be due to several reasons, such as changes in conditions, measurement errors, or random variations, and do not necessarily mean the experiment is flawed or a set of results should be ignored. Both sets of results should be compared to determine potential differences.

When an experiment is repeated and the new results are different from the original results, it's safe to assume that both sets of results may be inaccurate for a variety of reasons (Option C). This does not necessarily imply that the experiment is flawed and must be redesigned, nor that the results from the second experiment should be ignored.

In science, reproducibility and consistency are key. There could be various factors leading to differing results, such as changes in conditions, measurement errors, or random variations. It is crucial to carefully review both sets of experimental results and determine if any variables or factors might have considerably altered between the experiments. In some cases, multiple repeats of the experiment may be required to arrive at a consistent result.

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Answer:

The Answer is B

Explanation:

Because a cell is the small unit of life it is the one that help us.

A cell is the smallest unit of life, performing various functions in living organisms. Cells make up tissues in the human body.

According to Mike's mom, a cell is the smallest unit of life. It is a microscopic structure that makes up all living organisms, including plants and animals.

Cells perform various functions, such as energy production and protection. They contain different components, including a nucleus, cytoplasm, and cell membrane.

For example, in a human body, cells form different types of tissues, such as muscle tissue or nerve tissue, which have specific functions in the body.

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Answer:

the correct answer would be A.

Explanation: