Select the two true statements about natural selection. Natural selection makes less advantageous variations become more advantageous over many generations. A population's environment affects the outcome of natural selection. Natural selection always makes a population gain new advantageous variations. Natural selection can change which variations are more common in a population over time. Submit

Answer:

At STP (standard temperature and pressure), one mole of any gas occupies 22.4 liters. Therefore, to determine the number of moles of helium gas that would occupy 60 L at STP, we can use the following conversion factor:

1 mole He gas = 22.4 L He gas at STP

So, we can set up the following proportion:

x moles He gas / 60 L He gas = 1 mole He gas / 22.4 L He gas

where x is the number of moles of helium gas we want to find.

To solve for x, we can cross-multiply and simplify:

x moles He gas = (60 L He gas)(1 mole He gas / 22.4 L He gas)

x moles He gas = 2.68 moles He gas (rounded to two decimal places)

Therefore, 2.68 moles of helium gas would occupy 60 L at STP.

When CH3-CH2-CH2-CH2-CHO (butyraldehyde) reacts with CH2CH2OH (ethylene glycol), a hemiacetal is formed.

The reaction can be written as:

CH3-CH2-CH2-CH2-CHO + CH2CH2OH → CH3-CH2-CH(OH)-CH2-CH2OH

The hemiacetal product is CH3-CH2-CH(OH)-CH2-CH2OH.

If the reaction continues, a second molecule of ethylene glycol can react with the hemiacetal to form an acetal:

CH3-CH2-CH(OH)-CH2-CH2OH + CH2CH2OH → CH3-CH2-CH(OC2H4)-CH2-CH2OH + H2O

The acetal product is CH3-CH2-CH(OC2H4)-CH2-CH2OH.

Molecules can exist in different states, including gases, liquids, and solids. The physical and chemical properties of a molecule are determined by the types of atoms it contains, the way the atoms are arranged, and the types of chemical bonds between them. The study of molecules and their properties is an important area of chemistry and plays a crucial role in many areas of science and technology, including materials science, pharmaceuticals, and biochemistry.

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Answer:

molecular formula = C₂₇H₃₆O₄₅

Explanation:

In order to find the molecular formula of a compound from its empirical formula, we need to know the number of "empirical formula units" that are in the molecular formula.

To find the number of empirical formula units, n,  we use the following formula:

[tex]\boxed{\mathrm{n = \frac{molar \ mass}{empirical \ formula \ mass}}}[/tex].

The empirical formula mass is simply the molar mass of the compound that is represented by the empirical formula. Therefore, in this case,

Empirical formula mass of C₃H₄O₅ = (12 × 3) + (1 × 4) + (16 × 5)

                                                         = 36 + 4 + 80

                                                         = 120

Next, we can find the value of n using the above formula:

n = [tex]\frac{1080.54}{120}[/tex]

  = 9.00

Now that we know the number of empirical formula units (n) present in the molecular formula, we simply have to multiply the number of each element present in the empirical formula by n:

Molecular formula = (empirical formula)ₙ

⇒ Molecular formula = (C₃H₄O₅)₉

                                   = C₂₇H₃₆O₄₅

Therefore, the molecular formula of the secret compound is C₂₇H₃₆O₄₅.

5 Moles of HNO₂ is produced from 5 moles of NaNO. This is taken out by molar reaction and stochiometric coefficients .

A mole, like all units, must be defined or founded on something reproducible. The mole's current definition is defined, but it was previously based on the amount of atoms in a sample of the isotope carbon-12. A mole is now defined as Avogadro's number of elements, which is 6.02214076 × 10²³. For all practical purposes, one mole of a compound in grams is roughly equivalent to one molecule of the compound in Daltons.

Originally, a mole was defined as the amount of anything that contains the same number of elements as 12.000 grams of carbon-12. That number of elements is known as Avogadro's Number, which is approximately 6.02x10²³. 6.02x10²³carbon atoms constitute a mole.

Since the reaction of NaNO and HNO₂ is a 1:1 ratio, 5 moles of NaNO would produce 5 moles of HNO₂.

NaNO + HNO₂ → NaNO₂

The balanced equation for the reaction is:

2 NaNO + HNO₂ → 2 NaNO2

Therefore, if you start with 5 moles of NaNO, 5 moles of HNO₂ will be produced.

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Substance is soluble in water is D. NH₄CI. Soluble in water means that is capable of dissolving in water.

Substance is soluble if it dissolves in certain fluids and the fluid [gas or liquid] (present in excess) is called solvent and substance dissolved in it is called solute which together forms solution. Process of dissolving is called the solvation.

If substance is soluble, then it implies that it can be dissolved in liquid. This means particles are broken down to become so small that we can no longer see them. Salt and sugar are examples of soluble materials. Opposite of soluble is insoluble ( that is a substance that cannot be dissolved).

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The balanced chemical equation for the reaction between Pb(NO3)2 and NaCl is:

Pb(NO3)2 + 2NaCl -> PbCl2 + 2NaNO3

In order for a chemical equation to be balanced, the number of atoms of each element in the reactants must be equal to the number of atoms of each element in the products.

In the given equation, there are one Pb atom, two Na atoms, two Cl atoms, two N atoms, and six O atoms on the left-hand side (reactants) of the equation. On the right-hand side (products) of the equation, there are one Pb atom, two Na atoms, two Cl atoms, two N atoms, and six O atoms.

To balance the equation, we need to adjust the coefficients (the numbers in front of the chemical formulas) so that the number of atoms of each element is the same on both sides. In this case, we need to add a coefficient of 2 in front of NaCl on the reactant side to balance the number of Cl atoms, which also adds 2 Na and 2 NO3 atoms. This gives us:

Pb(NO3)2 + 2NaCl -> PbCl2 + 2NaNO3

Now the equation is balanced because there are the same number of atoms of each element on both the reactant and product sides.

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The percent yield of aspirin is 51.6%.

The limiting reagent is salicylic acid, and the theoretical yield of aspirin is 12.2 g.

The percent yield of aspirin is 72.9%.

The theoretical yield of aspirin is 3.95 g, but the actual yield is 2.04 g.

The percent yield can be calculated using the formula:

percent yield = (actual yield / theoretical yield) x 100%

Substituting the values given in the question, we get:

percent yield = (2.04 g / 3.95 g) x 100%

percent yield = 51.6%

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The net formal charge on the given species ([tex]ClO_4[/tex]) is -1. From the diagram we can see that each oxygen atom has 3 pair of electrons and remaining are shared with the chlorine atom.

A charged species is a species that has an unequal number of protons and electrons, resulting in an overall charge. Examples of charged species include ions, radicals, and polar molecules. Ions are atoms or molecules that have gained or lost one or more electrons, resulting in a net charge while radicals are molecules or ions with an unpaired electron, resulting in a net charge.

Formal charge is calculated as = total number of valence electrons in free atom - number of non-bonding electrons - 1/2 (number of bonding electrons).

Free atom is chlorine with 7 valence electrons.

Oxygen has 8 electrons which are in pairs so, non-bonding electrons = 0

Number of bonding electrons = 14

formal charge on chlorine = 7 - 0 - 1/2(14) = 0

Formal charge on three oxygen atoms = 6 - 4 - 1/2(4) = 0

Formal charge on fourth oxygen atom = 6 - 6 - 1/2(2) = -1

net charge = 0 + 0 + (-1) = -1

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Answer: 4 L

Explanation:

Since no values other than pressure and volume change, we will use this equation.

Given in the problem we know:

[tex]P_1=2\\V_1=2.0\\P_2=1[/tex]

So, we are left with one variable to solve for.

[tex]2*2.0=1*V_2\\V_2=4 L[/tex]

Metals are typically solid at room temperature, have a shiny or metallic appearance, are good conductors of heat and electricity, and are malleable and ductile.

Nonmetals, on the other hand, can exist in all three states of matter at room temperature, are generally not shiny, and are poor conductors of heat and electricity. They tend to be brittle and cannot be easily drawn into wires or hammered into thin sheets.

Metalloids have properties that fall somewhere between those of metals and nonmetals. They may have a shiny or dull appearance, and their ability to conduct heat and electricity is generally between that of metals and nonmetals.

The position of an element in the periodic table can give you some clues about its classification. Metals are typically found on the left side and middle of the periodic table, nonmetals are found on the right side, and metalloids are located along the "stair-step" line that separates the metals and nonmetals.

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Answer: Melting point determination can be used to distinguish between a pure sample and an impure sample because the presence of impurities will usually lower the melting point of a substance.

Explanation:

When a pure substance is heated, it will begin to melt at a specific temperature known as its melting point. However, when an impure substance is heated, the presence of impurities will cause the melting point to decrease and the substance to melt over a range of temperatures.

Therefore, by comparing the melting point of a sample to the known melting point of a pure substance, we can determine whether the sample is pure or impure. If the sample has the same melting point as the pure substance, then it is likely pure. However, if the sample melts over a range of temperatures or at a lower temperature than the pure substance, then it likely contains impurities.

Based on the given information, it seems like we need help with creating a model of a repeating group of atoms for sample 2 using an atomic scale modeling tool. Here's an answer that includes the terms:

To create a model that represents a repeating group of atoms for sample 2, you should use the modeling tool at the atomic scale. Start by identifying the elements and their arrangement within the sample. Once you have this information, construct the repeating unit of atoms in the modeling tool, ensuring you accurately represent the positions, types, and bonding of the atoms involved. This model will help you visualize and better understand the structure of sample 2 at the atomic level.

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There are 32.1 grams of NO gas in the cylinder if a 5.00-l cylinder at 4.00 × 103 mm hg and 23°c.

To determine the number of grams of NO gas in a 5.00 L cylinder at [tex]4.00 × 10^3[/tex] mmHg and 23°C, we can use the ideal gas law:

PV = nRT

where P is the pressure, V is the volume, n is the number of moles of gas, R is the gas constant, and T is the temperature in Kelvin.

First, we need to convert the pressure to atmospheres and the temperature to Kelvin:

4.00 × [tex]10^3[/tex] mmHg = 5.26 atm (1 atm = 760 mmHg)

23°C = 296 K

Now we can rearrange the ideal gas law to solve for n:

n = PV/RT

n = (5.26 atm)(5.00 L)/(0.0821 L·atm/mol·K)(296 K) = 1.07 mol

Finally, we can convert from moles to grams using the molar mass of NO:

1.07 mol NO × 30.01 g/mol = 32.1 g NO

Therefore, there are 32.1 grams of NO gas in the cylinder.

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Reduce biodiversity: dumping sewage water into lakes as a result of excessive mining for minerals. Increase tree planting and ban fishing during the mating season to preserve biodiversity.

Encourage regional and local initiatives to combat biodiversity loss and promote its prevention. acquiring fewer products while ensuring that the ones you do purchase have a minimal impact on biodiversity. Investing in initiatives to advance biodiversity. Reducing waste of consumer products, including food, clothing, electrical equipment, and others can help to prevent the loss of biodiversity.

The majority of people understand biodiversity as a collection of distinct living things that are capable of breeding with one another. Examples of species include white-tailed deer, blue whales, sunflowers, white pine trees, and microscopic germs that are so small they cannot even be seen with the human eye.

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The limiting reactant when 2.00 g of Si and 1.50 g of N₂ react is Silicon (Si).

When two reactive compounds are mixed, then they react according to the stoichiometry of the balanced chemical equation between them. The reactant which is present in excess will be left unreacted after the completion of the reaction whereas the other corresponding reactant will name as the limiting reagent of the reaction.  

The molar mass of Si and N₂ is 28.08 g/mol and 28 g/mol.

The stoichiometry in which Si and N₂ is 3:2.

The mass of Si required to react with 1.50 g of N₂ is calculated as follows:

m(Si) = (3 × 28.08 g) / (2×28 g) × 1.50 g = 2.25 g

Since the calculated mass of Si is more than the given mass. Therefore we can say that Si is a limiting reagent.

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Elements on the periodic table are arranged in order of increasing atomic number.

This means that elements with lower atomic numbers have fewer valence electrons compared to elements with higher atomic numbers.

The elements are arranged into columns, or groups, based on the number of valence electrons they possess.

Elements in the same group generally have the same number of valence electrons, and elements in the same period (row) generally have one more valence electron than the element before it.

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The number of moles of CO in the given conditions is 2.51 moles. To calculate the number of moles of CO in the given conditions, we need to use the Ideal Gas Law equation:

PV = nRT

Where:

P = pressure

V = volume

n = number of moles

R = gas constant

T = temperature

First, we need to convert the given temperature in Celsius to Kelvin by adding 273.15:

T = 93°C + 273.15 = 366.15 K

Now we can plug in the values we have:

P = 4.52 atm

V = 20.0 L

R = 0.0821 L.atm/mol.K (gas constant for CO)

T = 366.15 K

n = PV/RT = (4.52 atm x 20.0 L)/(0.0821 L.atm/mol.K x 366.15 K) = 2.51 moles

Therefore, the number of moles of CO in the given conditions is 2.51 moles.

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Answer: pH=-log[H+]

pH=-log(2.5x10^-4)

pH=3.6

Explanation:

The experiment involved measuring the temperature changes of water and solutions containing sodium hydroxide and hydrochloric acid.

What is HCl?

HCl is the chemical formula for hydrogen chloride, a colorless, highly pungent gas. It is a strong acid that is commonly used in industry for a variety of applications, such as the production of PVC, food processing, and metal cleaning. It is also found naturally in the stomach as a component of gastric acid, where it aids in digestion. In water, HCl dissociates into H+ and Cl- ions, making it a strong electrolyte.

The purpose of the experiment was to determine the heat of solution of sodium hydroxide and the heat of neutralization between sodium hydroxide and hydrochloric acid, using various methods such as enthalpy, Qsurr & Qrxn, percent error, etc.

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Answer:

There are approximately 2.448 x 10^23 bromine atoms present in 35.2 g of CH2Br2.

Explanation:

The molar mass of CH2Br2 can be calculated as follows:

Molar mass of C = 12.01 g/mol

Molar mass of H = 1.01 g/mol

Molar mass of 2 Br = 2 x 79.90 g/mol = 159.80 g/mol

Therefore, the molar mass of CH2Br2 = 12.01 + 1.01 + 159.80 = 172.82 g/mol

Next, we can calculate the number of moles of CH2Br2 as follows:

moles of CH2Br2 = mass of CH2Br2 / molar mass of CH2Br2

moles of CH2Br2 = 35.2 g / 172.82 g/mol

moles of CH2Br2 = 0.203 moles

Finally, we can use Avogadro's number to calculate the number of bromine atoms present:

Number of bromine atoms = moles of CH2Br2 x 2 (since there are 2 bromine atoms per molecule of CH2Br2) x Avogadro's number

Number of bromine atoms = 0.203 x 2 x 6.022 x 10^23

Number of bromine atoms = 2.448 x 10^23 bromine atoms

Therefore, there are approximately 2.448 x 10^23 bromine atoms present in 35.2 g of CH2Br2.

The rate law can only be determined experimentally through the method of initial rates or by determining the order of the reaction with respect to each reactant. Therefore, the correct answer is D. none of these.

In chemical kinetics, the rate law is an equation that relates the rate of a chemical reaction to the concentration of reactants. It is usually determined experimentally by measuring the initial rates of the reaction under different conditions of reactant concentration, temperature, and pressure.

The general form of a rate law for a reaction involving one or more reactants can be written as follows:

rate = k[A]x[B]y[C]z...

where rate is the rate of the reaction, k is the rate constant, [A], [B], [C]... are the concentrations of the reactants, and x, y, z... are the orders of the reaction with respect to each reactant.

In the given reaction X → Z, we are not given any information about the specific reaction mechanism or the dependence of the rate on the concentrations of X and Z. Therefore, it is not possible to determine the rate law without experimental data.

To determine the rate law experimentally, we would need to measure the initial rates of the reaction under different conditions of reactant concentrations and analyze the data to determine the orders of the reaction with respect to each reactant. Based on the experimental results, we could propose a rate law that fits the data and determine the value of the rate constant k.

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My experiment with the cold and warm water changed my thinking about the Investigation Question because it showed me that the temperature of something can have a major impact on its properties.

For example, warm water was more buoyant than cold water, which meant that the warmer water was able to float objects that the colder water could not. This showed me that temperature can play a role in the physical properties of an object, making it either lighter or heavier, depending on the temperature.

My experiment with cold and warm water showed me that temperature can have a major effect on physical properties. When comparing cold and warm water, I found that the warmer water was more buoyant and was able to float objects that the colder water could not.

This demonstrated to me how temperature can impact the weight and buoyancy of an object, making it either lighter or heavier depending on the temperature.

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Answer:

1. Know your carbon footprint.

2. Travel less.

3. Eat less meat and focus on sustainably grown meat.

4. Create less waste.

5. Recycle more and create less trash.

Answer:

Iron-56 has the greatest binding energy per nucleon while Hydrogen-3 has the lowest based on the information in the graph of average binding energy per nucleon against number of nucleons in nucleus. We know that the the greater the amount of binding energy per nucleon the greater the nuclear stability is, thus Iron-56 is the most stable atom among Helium-4, Uranium-238 and Hydrogen-3.

Explanation:

Answer: .05

Explanation:

Answer: No the equation is not balanced

Explanation:

Here's how to balance it:

SrBr2 + (NH4)2CO3 → SrCO3 + 2NH4Br

The balanced equation has 1 strontium atom, 2 bromine atoms, 1 carbon atom, 3 oxygen atoms, 4 hydrogen atoms, and 2 ammonium ions on both sides of the equation.

Answer:

No, the given equation is not balanced. The balanced equation is:

SrBr₂ + (NH₄)₂CO₃ → SrCO₃ + 2NH₄Br

Explanation:

A chemical equation is a representation of a chemical reaction using chemical formulas and symbols. It shows the reactant(s) on the left side of the equation and the product(s) on the right side of the equation, separated by an arrow that indicates the direction of the reaction.

[tex]\underbrace{\sf SrBr_2 + (NH_4)_2CO_3} \;\;\longrightarrow \;\;\underbrace{\sf SrCO_3 + NH_4Br}\\\sf \phantom{ww.w}Rectant(s) \qquad \qquad \quad \quad Product(s)[/tex]

A balanced chemical equation has the same number of atoms of each element on both sides of the equation.

Coefficients are used to balance chemical equations and are placed in front of a chemical symbol or formula where needed.

Given chemical equation:

[tex]\sf SrBr_2 + (NH_4)_2CO_3 \;\;\longrightarrow \;\; SrCO_3 + NH_4Br[/tex]

Here, we need to balance the number of Sr, Br, N, H, C, and O atoms.

Check to see if there are the same number of atoms of each element on both sides of the equation:

[tex]\begin{array}{|l|c|c|c|c|c|c|}\cline{1-7}\vphantom{\dfrac12}\sf &Sr&Br&N&H&C&O\\\cline{1-7}\vphantom{\dfrac12}\sf Reactant&1&2&2&8&1&3\\\cline{1-7}\vphantom{\dfrac12}\sf Product&1&1&1&4&1&3\\\cline{1-7}\end{array}[/tex]

We can see that there are two bromine atoms on the left but only one on the right, so a coefficient of 2 needs to be added to NH₄Br on the right side of the equation:

[tex]\sf SrBr_2 + (NH_4)_2CO_3 \;\;\longrightarrow \;\; SrCO_3 + 2NH_4Br[/tex]

By adding the coefficient 2 to NH₄Br on the right side of the equation, the number of N, H and Br atoms on this side have been multiplied by 2. So we now have:

[tex]\begin{array}{|l|c|c|c|c|c|c|}\cline{1-7}\vphantom{\dfrac12}\sf &Sr&Br&N&H&C&O\\\cline{1-7}\vphantom{\dfrac12}\sf Reactant&1&2&2&8&1&3\\\cline{1-7}\vphantom{\dfrac12}\sf Product&1&2&2&8&1&3\\\cline{1-7}\end{array}[/tex]

As there are now the same number of atoms of each element on both sides of the equation, it is balanced.

Therefore, the balanced chemical equation is:

[tex]\sf SrBr_2 + (NH_4)_2CO_3 \;\;\longrightarrow \;\; SrCO_3 + 2NH_4Br[/tex]

The final volume of the NaOH solution is 500.0 mL.

To prepare a solution with a desired concentration, we can use the formula:

C = n/V

where C is the concentration in units of moles per liter (M), n is the number of moles of solute, and V is the volume of the solution in liters. Rearranging this formula, we get:

n = C x V

This formula tells us that we can find the number of moles of solute we need by multiplying the desired concentration (C) by the desired volume (V) of the solution.

To calculate the final volume of the NaOH solution, we can use the following equation:

M1V1 = M2V2

where M1 and V1 are the initial concentration and volume, respectively, and M2 and V2 are the final concentration and volume, respectively.

Substituting the given values into the equation, we get:

(0.300 M) (250.0 mL) = (0.150 M) (V2)

Solving for V2, we get:

V2 = (0.300 M × 250.0 mL) / (0.150 M)

V2 = 500.0 mL.

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Answer: They are sometimes called sighting errors

Explanation:

Answer: 24.356L/mol.

Explanation: Hence, the average experimental volume per mole of carbon dioxide for sodium carbonate and sodium bicarbonate is 24.356L/mol.