Dr. MArcus analyzed items on his physics test by calculating the proportion of students who got each item correct. Dr. Marcus was examining -item difficulty
-the guessing threshold
-item discriminability
-the antimode Ch6
Choose matching definition
a. item discriminability
b. mental age
c. item discrimination
d. item difficulty

Answer:

C. Hl

Explanation:

I just looked it up on the internet lol

Answer:

(C3H8) produces 660 g of CO2 and 360 g of H2O

Explanation:

The balanced chemical equation for the combustion of propane (C3H8) is:

C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g)

This equation tells us that for every molecule of propane (C3H8) that reacts with 5 molecules of oxygen (O2), 3 molecules of carbon dioxide (CO2) and 4 molecules of water (H2O) are produced.

So, if we have 220. g of propane (C3H8), we can find the amount of CO2 and H2O produced by using the mole ratio from the balanced equation:

1 mole C3H8 reacts with 5 moles of O2 to produce 3 moles of CO2 and 4 moles of H2O

We can find the number of moles of C3H8 by dividing the mass by the molar mass of C3H8 (44 g/mol):

220 g / 44 g/mol = 5 moles C3H8

So, the number of moles of CO2 and H2O produced can be found by multiplying the number of moles of C3H8 by the mole ratio:

3 moles CO2 = 3 moles CO2/1 mole C3H8 * 5 moles C3H8 = 15 moles CO2

4 moles H2O = 4 moles H2O/1 mole C3H8 * 5 moles C3H8 = 20 moles H2O

Finally, we can convert the number of moles of CO2 and H2O to grams by multiplying by their molar masses (44 g/mol for CO2 and 18 g/mol for H2O):

15 moles CO2 * 44 g/mol = 660 g CO2

20 moles H2O * 18 g/mol = 360 g H2O

So, the combustion of 220 g of propane (C3H8) produces 660 g of CO2 and 360 g of H2O.

1) There are 18 electrons and 20 protons

2) There are 21 neutrons hence the mass number is 41

An ion is created when an atom gains or loses one or more electrons. An atom is composed of a nucleus, which contains positively charged protons and neutral neutrons, and electrons, which orbit the nucleus.

If an atom gains one or more electrons, it becomes negatively charged and is known as an anion. If an atom loses one or more electrons, it becomes positively charged and is known as a cation.

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The empirical formula of a compound can be determined from the results of a combustion analysis. The empirical formula represents the simplest whole-number ratio of atoms in the molecule.

Here's how you can determine the empirical formula of the hydrocarbon based on the given information:

Determine the number of moles of CO2 produced:

moles = mass / molar mass

moles = [tex]22.0 g / (44.0 g/mol) = 0.5 mol[/tex]

Determine the number of moles of carbon in the sample:

moles of carbon = moles of CO2 produced / ratio of C:CO2

moles of carbon = [tex]0.5 mol / 1 : 1 = 0.5 mol[/tex]

Determine the number of moles of hydrogen in the sample:

moles of hydrogen = moles of CO2 produced / ratio of H:CO2

moles of hydrogen = [tex]0.5 mol / 1 : 2 = 0.25 mol[/tex]

Express the number of moles of each element as a whole number ratio:

moles of carbon / smallest number of moles = [tex]0.5 mol / 0.5 mol = 1[/tex]

moles of hydrogen / smallest number of moles =[tex]0.25 mol / 0.25 mol = 1[/tex]

So, the empirical formula of the hydrocarbon is CH, indicating that for every one carbon atom, there is one hydrogen atom in the molecule.

To find the molecular formula, you can use the empirical formula and the molar mass of the compound. The molecular formula is a multiple of the empirical formula and can be determined by dividing the molar mass of the compound by the empirical formula weight:

Empirical formula weight =[tex]12.0 g/mol + 1.0 g/mol = 13.0 g/mol[/tex]

Molecular formula multiple = molar mass / empirical formula weight

Molecular formula multiple = [tex]70 g/mol / 13.0 g/mol = 5.3846[/tex]

The molecular formula multiple is not a whole number, so we round up to the nearest whole number, which is 6. The molecular formula of the hydrocarbon is therefore 6 times the empirical formula, or C6H6.

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Answer:

divide it by

its molar mass

Explanation:

Answer:

Explanation:

"Qc" stands for "Reaction Quotient Concentration" and represents the ratio of the concentrations of products raised to their stoichiometric coefficients, divided by the ratio of the concentrations of reactants raised to their stoichiometric coefficients at a given point in a chemical reaction.

Qc is used in comparison to "Kc," the "Equilibrium Constant Concentration," to determine the direction in which a chemical reaction at equilibrium will shift. If Qc is less than Kc, the reaction will shift in the direction that increases the concentration of products, so as to reach a new state of equilibrium with Kc. Conversely, if Qc is greater than Kc, the reaction will shift in the direction that increases the concentration of reactants, so as to reach a new state of equilibrium with Kc.

In other words, if Qc is equal to Kc, the reaction is at its state of equilibrium, and any changes to the concentrations of reactants or products will cause the reaction to shift until a new state of equilibrium is reached with the updated Kc value. If Qc is not equal to Kc, the reaction will shift until it reaches a state of equilibrium with the updated Kc value.

Answer:

Chromium(III) phosphate trihydrate

Explanation:

The correct IUPAC name for CrPO4 · 3H2O is Chromium(III) phosphate trihydrate.

79942.6 calorie is the number of calories of energy absorbed by the water. The energy of an isolated system holds that energy could be transformed.

In physics, energy is indeed the quantitative quality that is imparted to a body or a physical system and is visible in the form of light and heat.

The energy of an isolated system holds that energy could be transformed in form but cannot be generated or destroyed. The joule is the International System of Units (SI) unit of measurement for energy (J).

Q = 2 kg × 4181 J / kg °C × 40°C

   = 334,480 J

   =79942.6 calorie

Therefore, 79942.6 calorie is the number of calories of energy absorbed by the water.

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Answer: 1.5 x 10^23 atoms

Explanation:

Answer:

1.505 x 10^23 atoms in 0.25 moles of silicon.

Explanation:

The number of atoms in 0.25 moles of silicon can be calculated as follows:

1 mole of any substance contains Avogadro's number of atoms. Avogadro's number is approximately 6.022 x 10^23 atoms/mole.

So, if we have 0.25 moles of silicon, the number of atoms can be calculated as follows:

0.25 moles x (6.022 x 10^23 atoms/mole) = 1.505 x 10^23 atoms

Therefore, there are approximately 1.505 x 10^23 atoms in 0.25 moles of silicon.

The theoretical yield of NO2 would be 22.08 grams.

Mole of 20.0 grams HNO3 = mass/molar mass

                                             = 20/63.01 = 0.32 mol

Mole of 20.0 grams NO = 20/30.01 = 0.67 mol

From the equation of the reaction, the mole ratio of HNO3 and NO is 2:1, thus, HNO3 is the limiting reactant.

The mole ratio of HNO3 and NO2 is 2:3, thus, the equivalent mole of NO2 formed would be:

3/2 x 0.32 = 0.48 mol

Mass of 0.48 mol NO2 = 0.48 x 46 = 22.08 grams

In other words, the theoretical yield of NO2 from the reaction is 22.08 grams.

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A.When strong acid is added,the concentration of hydronium ion immediately increases and after equilibrium ,the concentration of acetic acid will be higher  than before disturbance. Therefore, option A and D are correct.

A chemical that gives off hydrogen ions in water and forms salts by combining with certain metals are called as an acid.

B) The concentration of hydronium ion immediately decreases and after equilibrium ,the concentration of acetic acid will be lower  than before the disturbance.

As when strong base is added ,the hydronium ions from acetic acid reacts with base and therefore, their concentration decreases ,also after equilibrium ,the concentration of acetic acid will be lower than before the disturbance by following Le Chatelier's principle

C)When the temperature is decreased the reaction will move in forward direction as it is an exothermic reaction and so after equilibrium ,the concentration of acetic acid will be lower than before.

D) Sodium acetate is a basic salt and when it is added to the solution,it will dissociate to formed acetate ions and sodium ions and by the common ion effect ,After equilibrium ,the concentration of acetic acid will be higher than before the disturbance.

Thus, When strong acid is added, it has a greater tendency to dissociate, and thus the concentration of hydronium ion increases immediately according to Le Chatelier's principle.

Also, as the concentration of strong acid increases after equilibrium, the concentration of acetic acid increases.

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The balanced equation for the reaction of pentane (C5H12) with oxygen gas (O2) to produce carbon dioxide (CO2) and water (H2O) is: C5H12(l) + 8O2(g) → 5CO2(g) + 6H2O(g).

Reaction is the process of responding to a stimulus or situation. It can be physical, emotional, mental, or social. Reactions can vary depending on the individual and the context, and they can be positive or negative. Examples of reactions include feeling anger, joy, sadness, or fear when faced with a situation.

The ratio of reactants to products in this reaction is 1:5:6:8. This means that for every 1 molecule of pentane (C5H12), 5 molecules of carbon dioxide (CO2), 6 molecules of water (H2O), and 8 molecules of oxygen gas (O2) are required. Therefore, the answer to the question is 8, as 8 molecules of oxygen gas (O2) are needed to react with 1 molecule of pentane (C5H12).

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According to the question the answer is 1.204 x 10^24 molecules of water.

Molecules are the smallest particles of matter that can exist in a stable form. They are made of two or more atoms that are held together by chemical bonds. Molecules are the basis of all living things, and they are the building blocks of all matter. They come in a variety of shapes and sizes, and they can be composed of atoms of different elements. Molecules can be found in the air, in liquids, and in solids. They can be found in both organic and inorganic compounds, and they are essential components of life. Molecules play an important role in many chemical and biological processes, and they can be used to create new materials and products.

The number of water molecules in a block of ice containing 2.00 mol of water (H2O) can be calculated using the Avogadro's number, which is 6.02 x 10^23 molecules per mol. Therefore, the answer is 1.204 x 10^24 molecules of water.

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In the given reaction, carbon disulfide acts as an excess reagent and oxygen acts as a limiting reagent.

a) Oxygen is the limiting reactant.

b) 0.667 moles of carbon disulfide will still be present.

c) The formation of 0.333 moles of carbon dioxide and 0.667 moles of sulfur dioxide.

provided here,

To make 1 mole of carbon dioxide and 2 moles of sulfur dioxide from 1 mole of carbon disulfide, 3 moles of oxygen are required.

1.00 ol of carbon disulfide is the number of moles.

One mole of oxygen is equal to 1.00 mol.

The limiting reactant is oxygen. It will be totally eaten. (1.00 mol).

(B) An excess reactant is carbon disulfide. It will respond with

Oxygen reacts with 0.33 moles of carbon disulfide.

The extra reagent still present:

0.667 moles There will be a residue of carbon disulfide.

In order to make one mole of carbon disulfide and one mole each of carbon dioxide and sulfur dioxide, you need three moles of oxygen.

The carbon dioxide equivalent for 1 mole of oxygen is 1 mole/3, or 0.333 moles.

Sulfur dioxide is equal to 0.667 moles per 1.00 mol of oxygen (1.00 mol/(3/2)) mol.

Since carbon disulfide is an excess reagent in the above reaction, oxygen is a limiting reagent.

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Based on the model shown, the model is limited in its depiction of the condensation of gases as it does not show how the temporary fluctuating dipoles of the molecular electron clouds result in a net force of attraction between the molecules.

The correct option is D.

Intermolecular forces are the forces that exist between the molecules of substances such as gases, liquids, and solids. The intermolecular forces in gases are negligible.

Dipole-dipole interactions, London dispersion forces (commonly referred to as van der Waals forces), and hydrogen bonds are the three main types of intermolecular interactions.

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The circumstances listed below would accelerate diffusion within cells: 1. Boost the temperature. b. High concentration gradient e.

The spontaneous movement of particles from a high concentration area to a low concentration area is known as diffusion. In gases, liquids, and solids, it happens spontaneously as a passive transport mechanism. Temperature, concentration gradient, particle size, and the existence of barriers or impediments are some of the variables that affect the rate of diffusion. Several biological activities, such as the flow of gases into and out of cells, the transportation of nutrients and waste products across cell membranes, and the control of ion concentrations in cells, all depend on diffusion. Diffusion theory is fundamental to many disciplines, including chemistry, biology, physics, and engineering.

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Answer:

the final volume of the gas inside the cylinder after 0.500 mole has leaked out is 37.0 L.

Explanation:

The ideal gas law states that PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature. Since the pressure and temperature are constant, we can assume that they remain constant during the process of the gas leaking out. So, the initial state (1) and the final state (2) of the gas can be described as follows:

(1) PV1 = n1RT

(2) PV2 = (n1 - 0.500)RT

Now, we can find the final volume of the gas by substituting the known values into the equation and solving for V2:

V2 = (n1RT)/P = (1.90 * 8.31 * T)/P

V2 = (1.90 * 8.31 * T)/P = (1.90 * 8.31 * T)/P = 49.0

V2 = 49.0 L * (1.90 - 0.500) / 1.90

V2 = 37.0 L

Answer:

b. 500 m/s

Explanation:

The student needs to weigh out 18.055 g of chromium(II) nitrate.

What is mass?

Mass is a measure of the amount of matter in an object, typically measured in units of kilograms (kg), grams (g), or milligrams (mg). It is a scalar quantity, meaning it has magnitude but no direction.

(a) To prepare a 0.235 M solution of chromium(II) nitrate in 500 mL of water, we need to calculate the amount of chromium(II) nitrate that needs to be weighed out.

The formula weight of chromium(II) nitrate is Cr(NO3)2. Using the periodic table, we can find the atomic weights of the elements in this compound:

Cr: 52

N: 14

O: 16

So, the formula weight of chromium(II) nitrate is:

52 + 2(14 + 3(16)) = 154 g/mol

To prepare a 0.235 M solution, we need 0.235 moles of chromium(II) nitrate in 1 liter (1000 mL) of solution. In 500 mL of solution, we need:

0.235 moles/L x 0.5 L = 0.1175 moles

The mass of chromium(II) nitrate that contains 0.1175 moles can be calculated using the formula:

mass = moles x formula weight

mass = 0.1175 mol x 154 g/mol = 18.055 g

Therefore, the student needs to weigh out 18.055 g of chromium(II) nitrate.

(b) Option C, "Add a small amount of water to the volumetric flask and swirl until the salt sample has dissolved," would not be an expected step in the procedure used by the student. When preparing a solution in a volumetric flask, it is important to first add a portion of the solvent (in this case, water) to the flask, and then add the solute (chromium(II) nitrate) and mix it thoroughly to dissolve it. This is to ensure that the final volume of the solution is accurate, since the volumetric flask is calibrated to contain a specific volume of liquid only when filled to the mark after adding the solute.

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statements that describe Diels-Alder reaction. are A. The reaction is initiated by heat. D. The reaction involves the formation of three new C-C σ bonds. E. The reaction is concerted.

The Diels-Alder reaction is initiated by heat or light and involves the formation of new C-C sigma (σ) bonds. It is a concerted reaction, meaning that the breaking of the π bonds and the formation of the σ bonds occur simultaneously. The reaction is exothermic, not endothermic, as it releases energy upon the formation of the new bonds. Therefore, statements B and C are incorrect.

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Yes, all of these energy output objects can work with a turbine. Turbines are designed to convert energy from a source, such as the wind or flowing water, into useful forms of energy, such as electricity or movement.

Energy is an important concept in physics that describes the capacity of a physical system to do work. It is often described as the ability to do work and can be found in many forms, including kinetic energy, potential energy, thermal energy, electrical energy, and chemical energy. Kinetic energy is the energy of motion and is the result of an object's movement. Potential energy is the stored energy of an object due to its position or configuration. Thermal energy is energy contained in the movement of particles and is related to temperature.

This energy can then be used to power a variety of energy output objects, such as water heaters, light bulbs, and fans.

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Answer:

12.0 grams of hydrogen would produce 12.0 grams of water.

Explanation:

The reaction between hydrogen and oxygen to form water can be represented as follows:

2H2(g) + O2(g) -> 2H2O(l)

From the equation, it can be seen that for every 2 grams of hydrogen, 1 gram of oxygen is required to produce 2 grams of water. Therefore, if 12.0 grams of hydrogen reacts with oxygen, 12.0/2 = 6.0 grams of oxygen would be required. This amount of oxygen would produce 2 * 6.0 = 12.0 grams of water.

Answer:

Explanation:

the grams of water produced= 44 grames  

Answer:

0.54 M NaCl.

Explanation:

The final concentration of the mixture can be found using the formula for the dilution of a solution:

C1 * V1 + C2 * V2 = C_final * (V1 + V2)

where C1 and C2 are the initial concentrations of the two solutions, V1 and V2 are their volumes, and C_final is the final concentration of the mixture. Plugging in the given values, we get:

0.680 M * 279 mL + 0.450 M * 462 mL = C_final * (279 mL + 462 mL)

0.680 M * 279 mL + 0.450 M * 462 mL = C_final * 741 mL

0.680 M * 279 mL + 0.450 M * 462 mL = C_final * 0.741 L

Converting volumes to liters:

0.680 M * 0.279 L + 0.450 M * 0.462 L = C_final * 0.741 L

0.680 M * 0.279 L + 0.450 M * 0.462 L = C_final * 0.741 L

0.190982 + 0.209719 = C_final * 0.741 L

0.400701 = C_final * 0.741 L

Dividing both sides by 0.741 L:

0.400701 / 0.741 L = C_final

So, the final concentration of the mixture is 0.54 M NaCl.

If each household emits 60 metric tons of CO2 on average, and 21 metric tons are from transportation, the remaining CO2 emissions from a household would be 60 - 21 = 39 metric tons.

However, it is not possible to determine how many metric tons of CO2 are specifically from the use of buses, as this information is not specified. The 21 metric tons of CO2 emissions from transportation could come from a variety of sources, including buses, cars, trains, and airplanes. Without further information, it is not possible to determine exactly how many of the 21 metric tons of transportation-related CO2 emissions are specifically from the use of buses. To determine this information, you would need data that breaks down the total transportation-related CO2 emissions into smaller categories, such as emissions from individual modes of transportation. So, while it's known that each household emits an average of 60 metric tons of CO2 per year, with 21 of those metric tons being from transportation, it is not possible to determine the exact amount of CO2 emissions from the use of buses without additional information.

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Sometimes a neutral oxygen atoms gains electrons. The oxygen then becomes an anion with a negative charge.

All the atoms undergoes chemical reactions to attain the octet electronic configuration. It means that it tries to attain the configuration of noble gases, which has the most stable atoms.

Oxygen has 6 electrons in its outer shell. It accepts two more electrons to attain the configuration of neon. As it attains electrons the atoms become negatively charged ions, called anions. It will now become O²⁻.

So the oxygen atom attains electrons to become an anion, with negative charge.

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Answer:

168.64 grams of O2

Explanation:

To burn 46.8 grams of propane (C3H8), we need to find the amount of oxygen that reacts with it according to the balanced chemical equation:

C3H8 + 5O2 -> 3CO2 + 4H2O

From the equation, 1 mole of propane (C3H8) reacts with 5 moles of oxygen to form 3 moles of carbon dioxide and 4 moles of water. The number of moles of propane can be calculated as follows:

46.8 g C3H8 / (44.1 g/mol) = 1.054 mol C3H8

Therefore, 1.054 mol of propane (C3H8) requires 5 x 1.054 = 5.27 moles of oxygen to burn completely. To find the mass of the oxygen in grams, we multiply the number of moles by the molar mass of oxygen (O2):

5.27 moles O2 * 32.0 g/mol = 168.64 g O2.

So, 168.64 grams of oxygen are required to burn 46.8 grams of propane (C3H8).

The decomposition of H2O2 (hydrogen peroxide) can be described by the following reaction:

2H2O2 (aq) → 2H2O (l) + O2 (g)

This reaction follows first-order kinetics, so its rate of reaction is given by the following equation:

Rate = k[H2O2]

Where k is the rate constant and [H2O2] is the molar concentration of H2O2. The half-life of this reaction (the time required for [H2O2] to be reduced to half its initial value) is 1735 seconds.

Given that [H2O2] = 0.25 M, we calculate the rate of reaction as follows:

Rate = k[H2O2] = 1.0 x 10^-4 s^-1 × 0.25M = 2.5 x 10^-5 s^-1

Therefore, the instantaneous rate of H2O2 decomposition, when [H2O2] = 0.25 M, is 2.5 x 10^-5 s^-1.

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Answer:

142 can be expressed in scientific notation as 1.42 x 10².

Explanation:

The temperature of savannah's liquid to the nearest degree Fahrenheit  is 93.1

Temperature conversion formulas are defined as the conversion formulas for changing the value of temperature from one unit to another. They're colorful distinct temperature conversion styles. Kelvin, Celsius, and Fahrenheit are the most generally used scales for temperature dimension.

In science class, Savannah measures the temperature of a liquid to be 34° Celsius. Her teacher wants her to convert the temperature to degrees Fahrenheit.

The general formula to convert Celsius into Fahrenheit is

[tex]F = (C*\frac{9}{5}) +32[/tex]

Substitute C=34°,

[tex]F = (C*\frac{9}{5}) +32\\\\F = (34*\frac{9}{5}) +32\\\\F = (34*\ 1.8}) +32\\\\F = 61.2 +32\\\\F = 93.1[/tex]

Therefore, The temperature of Savannah's liquid to the nearest degree Fahrenheit is 93.1°.

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The balanced form of the chemical equation given above is as follows: C₂H₁₆ + 60₂ -> 6CO₂ (g) + 6H₂O(g).

A chemical equation is a symbolic representation of a chemical reaction where reactants are represented on the left, and products on the right.

A chemical equation is said to be balanced when the number of atoms of each element on both sides of the equation is the same.

According to this question, the equation for photosynthesis is given. The balanced form is as follows:

C₂H₁₆ + 60₂ -> 6CO₂ (g) + 6H₂O(g)

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