A student draws a diagram that describes how she thinks people see in the dark. Based on her drawing, she predicts that if people stay
in a totally dark room for a long time, eventually their eyes will adjust to the darkness and they will be able to see.
When she tries this experiment in a totally dark room, it turns out that her prediction was incorrect, and that she is unable to adjust to
the darkness. What should she do with her drawing?
Because her drawing does not accurately represent what really happens, she should make a new version of it that better predicts what she
actually experienced in the dark room.
Because her drawing was not useful in making an accurate prediction, she should discard it and not use drawings anymore to make
predictions.
Because her drawing represents how she thinks the world works, she should not change it but should be confident that she can use it to
make accurate predictions.
O
Because her drawing represents how she thinks the world works, she should use it to make other predictions and keep checking them until
one of them turns out to be correct

The newest bonanza for recycling scarce and toxic metals is to recover them from car batteries.

Recycled aluminum items cost more than 10 times more than metal metal is shiny. Thanks to their shiny appearance, they can be used in jewelry and decorations. Gold and silver are especially used in jewelry. In the past, mirrors were made of shiny metals, such as silver.

Silver is a very good reflector. It reflects around 90% of the light that hits it. All modern mirrors have a thin metal coating. Metals are usually more difficult to cut. Their hardness varies from metal to metal. Some metals, such as sodium, potassium and magnesium, are easy to cut.

In danger, metals can be beaten into thinner plates. This function is called editable. Most metals are malleable. Gold and silver metals are the most ductile metals. They can be forged into very thin sheets. Thin aluminum foils are widely used for safe packaging of medicines, chocolates and food.

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The addition of HX to an alkene is an example of an electrophilic addition reaction. This means that the reaction is regioselective, meaning that one direction of bond forming (or bond breaking) occurs in preference to all other directions.

In this reaction, the hydrogen halide molecule, HX, is an electrophile because the hydrogen atom is partially positive and is attracted to the electron-rich pi bond of the alkene. The pi bond acts as a nucleophile and donates a pair of electrons to the hydrogen halide molecule, which forms a new bond with the carbon atom that has the greater electron density, resulting in the formation of a carbocation intermediate.

The carbocation intermediate is then attacked by the halide anion, which acts as a nucleophile and donates a pair of electrons to the carbocation to form the final product. The regioselectivity of the reaction is determined by the stability of the carbocation intermediate, with the more stable carbocation being formed preferentially.

For example, in the addition of HBr to propene, the H+ ion is added to the carbon atom that has the greatest number of alkyl groups attached to it, resulting in the formation of the more stable 2-bromopropane product.

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3 g/mL is the density in grams per millititer to three significant figures.

To express the density of a cube of butter in grams per milliliter, we need to convert the weight from pounds to grams and the volume from cubic inches to milliliters.

1 pound is approximately equal to 453.592 grams, so the weight of the cube of butter in grams would be:
0.260 lb * 453.592 g/lb = 117.81992 g (rounded to three significant figures as 118 g)

1 cubic inch is equal to approximately 16.387 milliliters, so the volume of the cube of butter in milliliters would be:
\(1303 cubic inches * 16.387 mL/in^3 = 21,365.861 mL\) (rounded to three significant figures as 21,400 mL)

Therefore, the density of the cube of butter would be:
Density = Mass / Volume

= 118 g / 21,400 mL

= 0.00551 g/mL (rounded to three significant figures as 0.005 g/mL)

For the gem, we already have the mass as 600 g and the volume as 200 mL.

Therefore, the density of the gem would be:
Density = Mass / Volume

= 600 g / 200 mL

= 3 g/mL (rounded to three significant figures)

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Answer:

Compounds change properties when the number of atoms changes

The statement best explains the compound H₂O is not toxic to drink, but H₂O₂ is toxic to drink is compounds change properties when the number of atoms changes. The correct option is C.

H₂O is the chemical formula of water. It is made up of joining hydrogen and oxygen. Water is an essential compound of life. It is present in three forms on the earth.

H₂O₂ is the chemical formula of hydrogen peroxide. It is more viscous than water, and it is used as an antiseptic and used in cleaning cut areas and wounds.

When the atoms are more added to a compound. It changes its property because it becomes a new and different compound. Water and hydrogen peroxide are different compounds.

Thus, the correct option is C. compounds change properties when the number of atoms changes.

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Answer:

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The molecule/ion with a planar geometry among the given choices is SO42-.

Step-by-step explanation:
1. Determine the central atom: Sulfur (S) is the central atom in SO42-.
2. Calculate the number of electron pairs around the central atom: Sulfur has 6 valence electrons, and there are 4 oxygen atoms (each contributing 1 electron), plus 2 extra electrons from the 2- charge. So, there are (6+4+2)/2 = 6 electron pairs.
3. Identify the electron pair geometry: With 6 electron pairs, the electron pair geometry is octahedral.
4. Determine the molecular geometry: In SO42-, there are 4 bonding pairs (with O atoms) and 2 non-bonding pairs. In an octahedral arrangement with 2 non-bonding pairs, the molecular geometry is square planar, which is a planar geometry.

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(a) To get the pH of the media to 5.8, you would add NaOH solution. NaOH is used as a basic solution, and when it is added to a solution, it will increase the pH of the solution.

(b) The molecular weight of BA is 225.3. To prepare a 1M solution, you would have to weigh out 225.3 grams of BA.(c) To convert a 1M solution of BA to mg/mL, you can use the following equation: 1 mole = molecular weight in grams; 1000 millimoles = 1 mole. So, 1 M = 1000 mg/mL. Therefore, a 1M solution of BA is equivalent to 1000 mg/mL .(d) To convert a concentration of 1000 mg/mL .

Therefore, to calculate the weight required for a 5 mM solution, use the following formula :Mass of BA = molarity × volume × molecular weight= 5 × 0.001 × 225.3= 1.1265 grams(f) To convert a concentration of 5 mM to mg/mL, we use the following formula: Concentration (mg/mL) = (Concentration (mM) × Molecular weight) / 1000= (5 × 225.3) / 1000= 1.1265 mg/mL(g)

To convert a concentration of 1.1265 mg/mL to mg/L, we multiply by 1000, so 1.1265 mg/mL = 1126.5 mg/L.(h) Given that the stock solution of BA is 5 mM and the working solution is 0.2 mg/mL.

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Answer:

NH3 (ammonia ) is a base

Explanation:

Hope it helps you

The theoretical yield of silver chloride is 5.05 grams.

The percentage yield of silver chloride is 72.1%.

The balanced chemical equation for the reaction between silver nitrate and sodium chloride is:

AgNO3 + NaCl → AgCl + NaNO3

a. To determine the theoretical yield of silver chloride, we need to calculate the amount of silver chloride that would be produced if all of the silver nitrate reacted. We can use stoichiometry to do this.

From the balanced equation, we see that 1 mole of silver nitrate reacts with 1 mole of sodium chloride to produce 1 mole of silver chloride. The molar mass of silver nitrate is 169.87 g/mol, and the molar mass of silver chloride is 143.32 g/mol.

First, we need to convert the mass of silver nitrate given to moles:

moles of AgNO3 = 5.98 g / 169.87 g/mol = 0.0352 mol AgNO3

Since the reaction is with excess NaCl, we know that all the silver nitrate will react, so the theoretical yield of AgCl is:

theoretical yield = 0.0352 mol AgCl x 143.32 g/mol = 5.05 g AgCl

Therefore, the theoretical yield of silver chloride is 5.05 grams.

b. To determine the percentage yield of silver chloride, we need to compare the actual yield (3.64 g) to the theoretical yield (5.05 g), and calculate the ratio as a percentage:

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

percentage yield = (3.64 g / 5.05 g) x 100% = 72.1%

Therefore, the percentage yield of silver chloride is 72.1%.

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The statement regarding linoleic acid that is false is: "It has 20 carbons." In reality, linoleic acid has 18 carbons.

Linoleic acid is an essential omega-6 polyunsaturated fatty acid, which our body cannot produce on its own. It has two double bonds, specifically between carbons 9 and 10, and between carbons 12 and 13. These double bonds give linoleic acid its characteristic structure and properties.

Additionally, linoleic acid contains one carboxylic acid functional group at the end of the hydrocarbon chain, which is responsible for its acidic nature. Linoleic acid plays a vital role in our body, as it is a precursor to several other important fatty acids and serves as a component of cell membranes.

It also contributes to various physiological processes, such as inflammation and blood clotting. As an essential nutrient, linoleic acid must be obtained from our diet, primarily through plant-based sources such as vegetable oils, nuts, and seeds.

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We must use the molar ratio from the balanced chemical equation to calculate the amount of moles of NaNO3 produced by the complete reaction of 253 g of Na2CrO4.

First, using the molar mass of Na2CrO4, we need to determine how many moles there are. The formula for calculating the molar mass of Na2CrO4 is as follows:

Na: 2 atoms x 22.99 g/mol = 45.98 g/mol

Cr: 1 atom x 52.00 g/mol = 52.00 g/mol

O: 4 atoms x 16.00 g/mol = 64.00 g/mol

Total molar mass of Na2CrO4:

45.98 g/mol + 52.00 g/mol + 64.00 g/mol = 161.98 g/mol

Now, we can calculate the number of moles of Na2CrO4:

Number of moles = Mass / Molar mass

Number of moles = 253 g / 161.98 g/mol ≈ 1.56 mol Na2CrO4

The balanced chemical equation states that the molar ratio of Na2CrO4 to NaNO3 is 1:2. In other words, for every 1 mole of Na2CrO4 that reacts, 2 moles of NaNO3 are formed.

Therefore, 253 g of Na2CrO4 will react completely to yield about 3.12 moles of NaNO3.

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The temperature at which zirconium becomes superconducting in degrees celsius is -272.604° C.

Superconductivity is a phenomenon where a material loses all electrical resistance below a certain temperature, called the critical temperature. In other words, the electrical conductivity of a superconductor is infinite below this temperature.

This property has many practical applications, including in high-field magnets, electrical power transmission, and medical imaging equipment.

The underlying mechanism of superconductivity is not yet fully understood and is an active area of research in physics and materials science. There are several theoretical models that attempt to explain the behavior of superconductors, but more research is needed to fully understand the phenomenon.

Therefore, The temperature at which zirconium becomes superconducting in degrees celsius is -272.604° C.

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Answer:

d

Explanation:

i think

Bonding is demonstrated using electron dot diagrams by representing the valence electrons that form bonds.

Atoms in molecules are joined by a chemical bond.  Electrostatic forces between negatively charged electrons and positively charged atomic nuclei give rise to bonds.

An electron dot diagram is a representation of the arrangement of valence electrons around an atomic symbol.

The outermost shell contains valence electrons, which are electrons. By representing the valence electrons, which are the ones responsible for bonding, in electron dot diagrams bonding is demonstrated.

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Answer:

D)

Explanation:

CH4 + 2O2 = CO2 + 2H2O

1 (L CO2)= 32.5(L CO2)

1 (CH4) = 32.5 (L CH4)

By performing the necessary calculations and comparing the Q/K ratios, we can determine whether calcite or dolomite would form first in the given water sample with [Mg2+]∼0.10 mmol/L.

To determine which mineral, calcite or dolomite, would form first in the given water sample with [Mg2+]∼0.10 mmol/L, we need to calculate the saturation index (SI) for each mineral by comparing the Q/K ratios. The mineral with the higher SI will be more likely to precipitate first.

The saturation index (SI) is calculated by comparing the ion activity product (Q) with the equilibrium constant (K) for a particular mineral. In this case, we have the equilibrium reaction: CaMg(CO3​)2​⇌Ca2++Mg2++2CO3​2−.

For calcite, the Q/K ratio can be calculated using the concentration of Ca2+ and CO3​2− ions in the water sample. Since dolomite contains both Ca2+ and Mg2+ ions, we need to consider the concentration of Mg2+ as well.

By comparing the Q/K ratios for calcite and dolomite, we can determine which mineral has a higher saturation index (SI). The mineral with the higher SI will be more likely to precipitate first.

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Answer:

3

Explanation:

It's basically saying what number goes into 12 four times, I think.

Answer:

The temperature of the gas will be 2630 K

Explanation:

Charles's Law consists of the relationship that exists between the volume and the temperature of a certain quantity of ideal gas, which is maintained at a constant pressure, by means of a constant of proportionality that is applied directly. For a given sum of gas at a constant pressure, as the temperature increases, the volume of the gas increases and as the temperature decreases, the volume of the gas decreases because the temperature is directly related to the energy of the movement of the gas molecules. .

In summary, Charles's law is a law that says that when the amount of gas and pressure is kept constant, the ratio that exists between the volume and the temperature will always have the same value:

\(\frac{V}{T} =k\)

Assuming that you have a certain volume of gas V1 that is at a temperature T1 at the beginning of the experiment, by varying the volume of gas to a new value V2, then the temperature will change to T2, and it will be fulfilled:

\(\frac{V1}{T1} =\frac{V2}{T2}\)

In this case:

Replacing:

\(\frac{130 L}{4023 K} =\frac{85 L}{T2}\)

Solving:

\(T2=85 L*\frac{4023 K}{130 L}\)

T= 2630 K

The temperature of the gas will be 2630 K

Answer:

Wind depositing sand to build up sand dunes.

Explanation:

Answer:

Nitrogen forms many thousands of organic compounds. Most of the known varieties may be regarded as derived from ammonia, hydrogen cyanide, cyanogen, and nitrous or nitric acid. The amines, amino acids, and amides, for example, are derived from or closely related to ammonia.

Answer:

Nitrogen is a non metallic chemical element with formula N and atomic mass 14 g/mol.

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(a) EDTA is the most widely used chelating agent in titrations due to its ability to form stable complexes with a wide range of metal ions, including those of calcium, magnesium, iron, and zinc. (b)  the molar concentration of the EDTA titrant is 0.008391 M.

a) The stability constants of these complexes are high, which means that EDTA can effectively chelate metal ions even in dilute solutions. Additionally, EDTA has a relatively low molecular weight and can be easily dissolved in water, making it a convenient and versatile chelating agent for titrations.

(b) First, we need to calculate the molar concentration of Ca²+ in the solution. The mass of CaCO3 used to prepare the solution is:

mass of CaCO3 = 0.3571 g

The molar mass of CaCO3 is:

molar mass of CaCO3 = 100.09 g/mol

Using these values, we can calculate the number of moles of CaCO3:

moles of CaCO3 = mass of CaCO3 / molar mass of CaCO3

                = 0.3571 g / 100.09 g/mol

                = 0.003569 mol

Since the solution was diluted to a final volume of 500 mL, the molar concentration of Ca²+ is:

molar concentration of Ca²+ = moles of CaCO3 / final volume

                           = 0.003569 mol / 0.500 L

                           = 0.007138 M

During the titration, the EDTA reacts with the Ca²+ ions in the solution according to the following stoichiometry:

Ca²+ + EDTA⁴⁻ → CaEDTA²⁻

To determine the molar concentration of EDTA, we need to use the volume of EDTA solution required to reach the end point of the titration. This volume is:

volume of EDTA solution = 42.63 mL = 0.04263 L

We also know that the molar concentration of Ca²+ in the solution is 0.007138 M. Since the stoichiometry of the reaction is 1:1, the moles of EDTA used in the titration are equal to the moles of Ca²+ in the solution. Therefore, the molar concentration of EDTA is:

molar concentration of EDTA = moles of EDTA / volume of EDTA solution

                          = moles of Ca²+ / volume of EDTA solution

                          = molar concentration of Ca²+ × volume of Ca²+ solution / volume of EDTA solution

                          = 0.007138 M × 0.05000 L / 0.04263 L

                          = 0.008391

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Answer:

Silver (Ag)

Explanation:

The electronic configuration of copper is shown below;

[Kr]4d10 5s1

We can see that there is only one 5s1 electron. Hence Ag^+ tends to display a pseudo noble gas configuration. This pseudo noble gas configuration explains why silver is prevalent in the +1 oxidation state.

The other transition metals have many stable oxidation states found in nature. Chromium is observed both in +3 and +6 oxidation states. Iron is found in +2 and +3 oxidation states and copper is mostly stable in the +2 oxidation state since the +1 oxidation state readily disproportionate.

Hence silver tends to have only a single ionic charge for reasons aptly stated above.

The statement 'what stars are made of' is an example of a question that could be answered using cosmological models.

Cosmological models are scientific models to understand the forces that shape the structure of the universe.

The cosmological model answers diverse types of inquiries such as ''what stars are made of' because this model describes the composition of celestial bodies (including stars) in the universe.

The cosmological model can examine different questions about the universe including its composition, structure, evolutionary trajectories, etc.

In conclusion, the statement 'what stars are made of' is an example of a question that could be answered using cosmological models.

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The concentration of NO3-N in mg/L = 10 mg/L.

The given water sample contains 10 mg NO3/L.

To find the concentration of NO3 in millimoles/L:

1 mg = 1/1000 g1 mole of NO3 contains 1 + 3x16 = 61 g NO3So, 1 g NO3 = 1/61 mole NO3

Thus, 10 mg NO3 contains (10/1000) * (1/61) mole of NO3= 0.000163934426 mole of NO3

Therefore, the concentration of NO3 in millimoles/L = 0.000163934426 * 1000= 0.163934426 millimoles/L

To find the concentration of NO3-N in mg/L:1 mole of NO3 contains 1 mole of N= 14 g N

Thus, 1 g NO3-N = 1/14 mole of NO3-N

Therefore, 10 mg NO3-N contains (10/1000) * (1/14) mole of NO3-N= 0.000714285714 mol of NO3-N

Therefore, the concentration of NO3-N in mg/L = 0.000714285714 * 14000= 10 mg/L.

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Answer:

Neutrons

Explanation:

We can use the formula for heat released:

Q = mcΔT

where Q is the heat released, m is the mass of the sample, c is the specific heat of the material, and ΔT is the change in temperature.

Plugging in the given values, we have:

113.8 J = m(0.240 J/g°C)(-45.0°C)

Simplifying:

m = 113.8 J / (0.240 J/g°C * -45.0°C)

m = 106.5 g

Therefore, the mass of the silver sample is 106.5 g.

When a chemical reaction happens, the atoms in the reactants are rearranged to create compounds with various chemical characteristics. Although identical atoms are present in both the reactants and the products, sodium chloride was produced by rearranging the atoms in the reactants. The reactants lacked sodium chloride.

Sodium is a soft, silver-colored metal that may be sliced with a knife. With water, pure sodium metal reacts violently (and even explosively), creating sodium hydroxide, hydrogen gas, and heat.

2Na(s)  +  2H₂O(l)  ⟶  2NaOH(aq)  +  H₂(g)

Chlorine is a poisonous yellow-green gas with a pungent smell.

But when sodium and chlorine combine, they create sodium chloride, or table salt, which is known to practically everyone in the world.

2Na(s)  +  Cl₂(g)  ⟶  2NaCl(s)

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