Dentists use a soft, clay-like material to make a filling for a cavity. The filling stays soft under the light of the dentist’s lamp, but it hardens when the dentist shines an ultraviolet flashlight on it. Why does light from the ultraviolet flashlight harden the filling when light from the lamp does not?

The volume of the sodium hydroxide solution needed for the reaction is 0.3 L

We'll begin by writing the balanced equation for the reaction.

H₂X + 2NaOH → 2H₂O + Na₂X

From the balanced equation above, the following data were obtained:

From the question given above, the following data were obtained:

MaVa / MbVb = nA / nB

(0.1 × 0.3) / (0.2 × Vb) = 1/2

0.03 / (0.2 × Vb) = 1/2

Cross multiply

0.03 × 2 = 0.2 × Vb

0.06 = 0.2 × Vb

Divide both side by 0.2

Vb = 0.06 / 0.2

Therefore, the volume of NaOH needed for the reaction is 0.3 L

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Answer:

Explanation:

The Carnot engine is a theoretical or conceptual heat engine that has a higher efficiency than any practical or theoretical heat engine working between the same temperature range. The theoretical efficiency of a Carnot engine is considered as the highest efficiency and no practical heat engines can operate at that efficiency. A Carnot engine draws heat energy, performs useful work and the leftover energy is released from the working substance. According to the second law of thermodynamics, there must be a temperature gradient between the heat energy drawing point and release point of the heat engine.

aused by the weight of the huge numbers of air molecules that make up the atmosphere. ... When air pressure is low, air flows together and then upward where it converges, rising, cooling, and forming clouds.

Answer:

Explanation:

The weather events happening in an area are controlled by changes in air pressure. Air pressure is caused by the weight of the huge numbers of air molecules that make up the atmosphere. ... When air pressure is low, air flows together and then upward where it converges, rising, cooling, and forming clouds.

Answer:

Liquid X is neutral and Liquid Y is a base

Explanation:

Acid: pH<7

Neutral: pH=7

Base: pH>7

Answer:

The pressure of the flask is 0.73 atm.

Explanation:

To solve this question, we should use the ideal gas law: PV=nRT, where P represents the pressure (in atm in this case), V represents the volume (in L), n represents the number of moles of gas, R is the ideal gas constant, and T represents the temperature (in K).

Before we can plug our values into the equation, we must convert so that our units cancel out. First, we should convert our temperature from degrees Celsius to degrees K.

25°C + 273.15 = 298.15K

Next, we should convert the 0.12 g He to moles using the molar mass of He.

0.12 g He * (1 mole He/4.003 g He) = 0.029978 mol He

Now, we can plug in the values into the equation and solve for the pressure.

PV = nRT

P = (nRT)/V

P = (0.029978 mol He * 0.0821 L*atm/mol*K * 298.15 K)/(1.0 L)

P = 0.73 atm

Therefore, the correct answer is 0.73 atm.

Hope this helps!

Answer:

c

Explanation:

Empirical is the simplest whole number ratio of elements in a compound. Molecular formula is n times the empirical formula, where n is integers 1,2,... The molecular formula is  C[tex]_4[/tex]H[tex]_6[/tex]Br[tex]_4[/tex]. The correct option is option E.

Empirical formula gives the proportion of the element that is present in a compound. It does not give information about the actual number or the arrangements of the atoms.

n=empirical formula mass÷ molecular formula mass

n=1,2,3....

empirical formula mass = 373.69 g/mol

molecular formula mass=  186.85 g/mol

substituting all the given values in the above formula, we get

n=  186.85 g/mol÷  373.69 g/mol

   = 2

Multiply C[tex]_2[/tex]H[tex]_3[/tex]Br[tex]_2[/tex] by 2, which comes out to be C[tex]_4[/tex]H[tex]_6[/tex]Br[tex]_4[/tex].

Therefore, the molecular formula is C[tex]_4[/tex]H[tex]_6[/tex]Br[tex]_4[/tex]. The correct option is option E.

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Answer:

Boyle's Law: When the pressure of a gas increases, the volume of the gas will decrease as long as the temperature and amount of gas are constant.

So basically pressure is inversely proportional to Volume, when one increases, the other decreases, vice versa.

Equation: [tex]P_{1} V_{1} = P_{2} V_{2}[/tex]

Charles Law: When the temperature of a gas increases, the volume of a gas will also increase if the pressure and amount of gas are constant.

So basically Temperature and volume are directly proportional.

Equation: [tex]\frac{V_{1}}{T_{1}} = \frac{V_{2} }{T_{2} }[/tex]

Gay Lussac's Law: When the temperature of a gas increases, the pressure of a gas also increases when volume and the amount of gas remain constant.

Basically, Temperature and Pressure are directly proportional.

Equation: [tex]\frac{P_{1}}{T_{1}} = \frac{P_{2} }{T_{2} }[/tex]

Avogadro's Law: The most intuitive gas law. When you increase the amount of gas, the volume will also increase.

Meaning the moles (amount of gas) is directly proportional to volume.

Equation: [tex]\frac{V_{1} }{n_{1} } = \frac{V_{2} }{n_{2} }[/tex] (n stands for moles)

There is a combined gas law and ideal gas law but those are just the gas laws mentioned above but combined together. These should be everything.

Answer:

Boyle Law is when pressure and volume have a reverse relationship when temperature is the same.Charles law is basically when volume and temperature have a relationship when the pressure is the same.Lussac Law is I think just when I pressure and temperature is directly tied together when the volume stays the same.I dont think there is any "avogadro law", there is only pressure volume and temperature.

Please give brainliest thanks :D

The characteristics of the subatomic particles allow to find which is the correct answer:

B)  Subatomic particles don’t follow the same laws of physics as large objects.

Subatomic particles are the contributors to atoms, the main three being electrons, protons, and neutrons. The movement of these particles is described by the Schrodinger equation, the result of which is wave function.

To obtain the physical function of the wave mergers, the probability function must be constructed.

                        P = Ф* Ф

therefore the movement of the subatomic particulars is probabilistic at all times, when a large number of them join the mean value of this probability closer to the macroscopic movement.

Let's examine the claims.

A) False. The macroscopic motion of objects is the mean value of the microscopic motion, which with increasing size is deterministic and predictable.

B) True. Subatomic particles follow the rules of the Schrodinger equation and macroscopically Newton's second law.   Inconsequently they use different laws or to describe

C) False the most important force is electrostatic.

D) false. Large particles can be measured with a ruler, but sublimation that are orders of magnitude smaller require instruments of great pressure and complexity.

In conclusion using the characteristics of the subatomic particle we can find what the correct answer is;  

B)  Subatomic particles don’t follow the same laws of physics as large objects.

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Answer:

intra moleculer force is the force which you can't see

Taking into account the reaction stoichiometry and STP conditions, the volume of nitrogen monoxide gas that is created at STP when 32.2 g of solid copper reacts with excess nitric acid is 7.5677 L.

The balanced reaction is:

3 Cu(s) + 8 HNO₃(aq) → 3 Cu(NO₃)₂ (aq) + 4 H₂O(l) + 2 NO(g)

By reaction stoichiometry, the following amounts of moles of each compound participate in the reaction:

The molar mass of the compounds is:

By reaction stoichiometry, the following mass quantities of each compound participate in the reaction:

The STP conditions refer to the standard temperature and pressure, which values are 0 °C and 1 atmosphere and are reference values for gases. In these conditions 1 mole of any gas occupies an approximate volume of 22.4 liters.

The following rule of three can be applied: if by reaction stoichiometry 190.62 grams of Cu form 2 moles of NO, 32.2 grams of Cu form how many moles of NO?

moles of NO= (32.2 grams of Cu× 2 moles of NO)÷ 190.62 grams of Cu

moles of NO= 0.3378 moles

Then, 0.3378 moles of NO are formed.

Now, you can apply the following rule of three: if by definition of STP conditions 1 mole of NO occupies a volume of 22.4 liters, 0.3378 moles occupies how much volume?

volume= (0.3378 moles× 22.4 L)÷ 1 mole

volume= 7.5677 L

Finally, the volume of NO created is 7.5677 L.

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The volume of precipitating reagent, HCl required to precipitate silver in the form of AgCl from 2,000 g of an alloy containing 22% by weight of Ag is 0.530 L

In order to determine the volume of precipitating reagent, HCl required to precipitate silver in the form of AgCl from 2,000 g of an alloy containing 22% by weight of Ag, the following steps are followed:

Step 1.

The concentration of the HCl solution is calculated using the formula:

Percentage purity of HCl = 36% = 0.36

specific gravity, r = 1.17 g/cm³

molar mass of HCl = 36.5 g/mol

Concentration of HCl = 0.36 * 1.17 * 1000 / 36.5 * 1

Concentration of HCl = 11.53 mol/L

Therefore, 1 L of HCl solution contains 11.53 moles of HCl

Step 2:

The equation of the dissociation of HCl solution is given below:

1 mole of HCl produces 1 mole of Chloride ions, Cl⁻

Equation of reaction between Silver in the alloy and HCl is given as follows:

A white precipitate of AgCl is formed but hydrogen gas is not formed as Silver is a less reactive metal.

1 mole of HCl produces 1 mole of Cl⁻ which reacts with 1 mole of Ag to produce 1 mole of AgCl precipitate.

Step 3: Determine the mass and number of moles of silver in the alloy

Mass of silver in 2000 g alloy = 0.22 * 2000 g

Mass of silver in 2000 g alloy = 440 g

Number of moles of silver in 440 g of silver is determined using the formula below:

molar mass of silver = 108 g/mol

number of moles of silver = 440 /108

number of moles of silver in the alloy = 4.074 moles

Step 4: Calculate the volume of HCl required

Since 1 mole of Cl⁻ ions react with 1 mole of Ag; 4.074 moles of Cl⁻ ions will be required to react with 4.074 moles of Ag.

1 L of HCl solution contains 11.53 moles of Cl⁻

Volume of HCl solution that contains 4.074 moles of Cl⁻ = 4.074 * 1L/11.53

Volume of HCl that contains 4.074 moles of Cl⁻ = 0.353 L

Since 1.5 times the amount of precipitating reagent HCl is required, volume of HCl required = 1.5 * 0.353 L

Volume of precipitating reagent HCl required = 0.530 L

Therefore, the volume of precipitating reagent, HCl required to precipitate silver in the form of AgCl from 2,000 g of an alloy containing 22% by weight of Ag is 0.530 L

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Answer:

1 used in paint , toothpaste

2 used in fireworks and magnets

3 used to manufacture alloys

Answer:

C. 10.540 moles

Explanation:

divide grams by molar mass to get moles

Answer:

I think B) electronegativity is the correct answer.

Electronegativity is the property which is  used to determine the degree of polarity between two bonded atoms. Therefore, the correct option is option B.

Polarity is the dispersion of electrical charge over the atoms linked by a chemical bond. Bonds between identical atoms, such as H2, are electrically homogeneous in the sense that both hydrogen atoms are electrically neutral, but bonds between different atoms are electrically inequivalent.

Electronegativity is the property which is  used to determine the degree of polarity between two bonded atoms. The relative electronegativities of the elements determine the polarity of a bond. Electronegativity is the ability of an element's atom to attract electrons to itself when it is part of a compound.

Therefore, the correct option is option B.

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The molarity of aqueous lithium bromide, LiBr solution is 0.2 M

We'll begin by calculating the number of mole of Pb(NO₃)₂ in the solution.

Mole = Molarity x Volume

Mole of Pb(NO₃)₂ = 0.25 × 0.01

Mole of Pb(NO₃)₂ = 0.0025 mole

Next, we shall determine the mole of LiBr required to react with 0.0025 mole of Pb(NO₃)₂

Pb(NO₃)₂ + 2LiBr —> PbBr₂ + 2LiNO₃

From the balanced equation above,

1 mole of Pb(NO₃)₂ reacted with 2 mole of LiBr.

Therefore,

0.0025 mole of Pb(NO₃)₂ will react with = 2 × 0.0025 = 0.005 mole of LiBr

Finally, we shall determine the molarity of the LiBr solution

Molarity = mole / Volume

Molarity of LiBr = 0.005 / 0.025

Molarity of LiBr = 0.2 M

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Answer:

F,E,D,C, B, A, G, H, I

Explanation:

I think. It goes bottom to top. the fault probably cause g to happen and maybe h but mattering on what caused what I am not positive

Answer:

If you are looking for the answer, for the question.

Earthquakes trigger tsunamis when the seismic activity causes the land along fault lines to move up or down

Answer:

I think It is Covalent. Not 100% sure but like 90% sure.

Answer:

The speed of light, c, equals the wavelength, λ (pronounced lambda), times the frequency, ν, (pronounced noo).

c=λν

c is a constant. It is usually given as 3.00×108 m/s or 3.00×1010 cm/s rounded to three significant figures.❤

Answer:

2CH3CHO + O2 → 2CH3COOH

Answer:

Create a flowchart of the various steps.

Explanation:

Answer:

A.

Explanation:

have a nice day^^ good morning

Based on the information given, the private savings will be $10000 and the gross domestic product is $63000.

From the information given, he following can be gotten:

Since, S = Y - C - G

11000 = Y - 48000 - G

Y - G = 48000 + 11000

Y - G = 59000

Budget surplus = T - G = 1000

5000 - G = 1000

G = 5000 - 1000 = 4000

The GDP will be:

Y - G = 59000

Y - 4000 = 59000

Y = 59000 + 4000 = 63000

Private savings = Y - T - C

Private savings = 63000 - 5000 - 48000

Private savings = 10000

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very low

Explanation:

Nuclear fusion is a nuclear reaction wherein small nuclei are combined to form heavier nuclei. This process constantly occurs in the sun, which is mainly composed of hydrogen and helium atoms.

Answer:

448mL AgNO3

Explanation:

M x V

n = 0.230 x .045 = 0.01

2AgNO3 + Na2S --> Ag2S+2NaNO3

1 mol Ag2S --> 2 moles AgNO3

.01 mol Ag2S --> ? moles AgNO3

.01x2/1=.02 moles AgNO3

Moles to L conversion is multiplying by 22.4L so we do .02 x 22.4=0.448L

Then we convert to mL so we multiply by 1000 (1000 x 0.448)

448mL AgNO3

There you go friend, good luck with chemistry :)