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?

Answers

Answer 1

Answer:

the clay will be melted by the light

Explanation:

because UV rays are hot but in a way, human skin can not feal pain


Related Questions


What is the molarity of a NaOH solution when 22.14 mL of 0.105 M oxalic acid is needed to
neutralize 25.0 mL of the base.

Answers

The molarity of the NaOH solution required for the reaction is 0.186 M

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

H₂C₂O₄ +2NaOH —> Na₂C₂O₄ + 2H₂O

From the balanced equation above,

The mole ratio of the acid, H₂C₂O₄ (nA) = 1

The mole ratio of the base, NaOH (nB) = 2

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

Volume of the acid, H₂C₂O₄ (Va) = 22.14 mL

Molarity of the acid, H₂C₂O₄ (Ma) = 0.105 M

Volume of the base, NaOH (Vb) = 25 mL

Molarity of the base, NaOH (Mb) =?

MaVa / MbVb = nA/nB

(0.105 × 22.14) / (Mb × 25) = 1/2

2.3247 / (Mb × 25) = 1/2

Cross multiply

Mb × 25 = 2.3247 × 2

Mb × 25 = 4.6494

Divide both side by 25

Mb = 4.6494 / 25

Mb = 0.186 M

Therefore, the molarity of the base, NaOH solution is 0.186 M

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The frequency light of 3.52*10-7

Answers

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.❤

If 0.45 mole oxygen gas occupies a volume of 1.5 L, what volumes will 2.0 moles of oxygen gas occupy at the same temperature and pressure?

please don't send YouT8ube link i need a solution

Answers

Answer:

1. How many moles of oxygen will occupy a volume of 2.5 liters at 1.2 atm and 25° C? PV = V (1.2 n. 0821) (298) = 123 mols 2.

2.0 moles of oxygen gas will occupy a volume of 6.67 L at the same temperature and pressure.

Moles is a unit of measurement used in chemistry to express the amount of a substance. It is a counting unit that represents the number of particles, such as atoms, molecules, or ions, in a given sample.

One mole of a substance is defined as the amount of that substance that contains Avogadro's number of particles, which is approximately 6.022 x 10²³. This number is based on the concept that atoms, molecules, and ions are extremely small and difficult to count individually, so using moles allows for a more practical and convenient representation of quantities.

Given:

Moles of oxygen gas (initial) = 0.45 mol

Volume of oxygen gas (initial) = 1.5 L

Moles of oxygen gas (final) = 2.0 mol

Volume of oxygen gas (final) = ?

Using the principle of molar volume, we can set up the following ratio:

(0.45 mol / 1.5 L) = (2.0 mol / V)

V = (1.5 L × 2.0 mol) / 0.45 mol

V = 6.67 L

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What types of orbitals are found in the third energy level?

Answers

Answer:

1 s-orbital, 3 p-orbital and 5 d-orbital

Answer:

there are a total of nine orbitals in a third energy level

Explanation:

Octane has a density of 0.703 g/ml. Calculate the mass of CO2(g) produced by burning one
gallon of octane. There are 3.79 liters to one gallon.

Answers

The mass of CO₂ gas produced during the combustion of one gallon of octane is 8.21 kg.

The given parameters:

Density of the octane, ρ = 0.703 g/mlVolume of octane, v = 3.79 liters

The mass of the octane burnt is calculated as follows;

[tex]m = \rho V\\\\m = 0.703 \ \frac{g}{ml} \times 3.79 \ L \ \frac{1000 \ ml}{L} \\\\m = 2,664.37 \ g[/tex]

The combustion reaction of octane is given as;

[tex]2C_8H_{18} + \ 25O_2 \ --> \ 16CO_2 \ + \ 18H_2O[/tex]

From the reaction above:

228.46 g of octane -------------------> 704 g of  CO₂ gas

2,664.37 of octane --------------------> ? of CO₂ gas

[tex]= \frac{2,664.37 \times 704}{228.46} \\\\= 8,210.3 \ g\\\\= 8.21 \ kg[/tex]

Thus, the mass of CO₂ gas produced during the combustion of one gallon of octane is 8.21 kg.

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Complete the balanced dissociation equation Cs2CO3

Answers

The balanced dissociation equation for Cs₂CO₃ is:

Cs₂CO₃(aq) —> Cs⁺(aq) + CO₃²¯(aq)

A dissociation equation is an equation showing the available ions present in a solution.

To obtain the dissociation equation, the compound must be dissolved in water to produce an aqueous solution.

The dissociation equation for Cs₂CO₃ can be written as follow

Cs₂CO₃(aq) —> Cs⁺(aq) + CO₃²¯(aq)

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What is important about the properties of a substance that has undergone a chemical
change?

Answers

The substances created during chemical reactions, on the other hand, do not simply revert to their initial state. The most essential thing to remember is that the makeup of a material does not change when it undergoes a physical change, but it does change when it undergoes a chemical change.

Answer:

the most important thing for you to remember is that in a physical change composition of a substance does not change and in a chemical change the composition of a substance does change

periodicity in chemical properties is based on atomic structure." explain.





Answers

Answer:

Periodicity is caused by regular and predictable variations in element atomic structure. ... The rows in the periodic table (the periods) reflect the filling of electrons shells around the nucleus, so when a new row begins, the elements stack on top of each other with similar please help me rank up

Periodicity means the repeating trends in properties of elements in a regular interval.  Precocity in chemical properties depends on the atomic structure because, the size, number of electrons, etc affects their reactivity.

What is periodicity?

Periodicity is the repetition in in trends in properties after a regular interval. In periodic table, all the elements are classified into different groups and periods.

Groups are vertical columns containing elements of same number of valence electrons and similar chemical and physical properties. Periods are horizontal rows where elements are arranges in the increasing order of atomic number.

Along a period the atomic size decreases, ionization energy and electronegativity increases. But down a group just the reverse for this happens.

In a chemical reaction only valence electrons are participating and the size and number of valence electrons etc affects the chemical reactivity of elements. That's why it is said like periodicity in chemical properties is based on the atomic structure.

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Which element represents magnetic properties?

Answers

Iron, cobalt and nickel!
Hope this helps!

Answer:Demagnetizing a magnet is also possible. Only a few substances are ferromagnetic; the most common ones are iron, cobalt and nickel and their alloys. The rare-earth metals neodymium and samarium are less common examples.

Explanation;

Of the following, ________ is the most volatile. Select one: C2F6 C2H6 C2I6 C2Cl6 C2Br6

Answers

Answer:

C2Br6

because bromine is a liquid volatile

According to the forces of attraction and boiling point C₂Br₆ is most volatile as its boiling point is very low.

What are forces of attraction?

Forces of attraction  is a force by which atoms in a molecule  combine. it is basically an attractive force in nature.  It can act between an ion  and an atom as well.It varies for different  states  of matter that is solids, liquids and gases.

The forces of attraction are maximum in solids as  the molecules present in solid are tightly held while it is minimum in gases  as the molecules are far apart . The forces of attraction in liquids is intermediate of solids and gases.

The physical properties such as melting point, boiling point, density  are all dependent on forces of attraction which exists in the substances.

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If the vapor pressure of water at 20.0 o C is 17.535 torr, and the atmospheric pressure measured by a barometer was 757.3 torr, what is the partial pressure of H2 in the gas mixture in a buret

Answers

Answer:

f the vapor pressure of water at 20.0 o C is 17.535 torr, and the atmospheric pressure measured by a barometer was 757.3 torr, what is the partial pressure of H2 in the gas mixture

Partial pressure of H2 in gas mixture is :

739.765 torr .

Explain total pressure?The overall pressure ptot is the total of all pressures in a reference system. This pressure, according to Bernoulli (see Fluid mechanics), consists of the static pressure p, the dynamic pressure pdyn, and the geodetic component ( g z) that exists in a fluid along a stream line in a frictionless flow.The total pressure of a gas mixture is the sum of its component gases' partial pressures: Ptot = ∑Pi = P1 + P2 + P3... ntot = total number of moles in the gas mixture (the sum of all ni).

Total  pressure of mixture =

Partial of hydrogen + Partial pressure of oxygen

Partial of Hydrogen = Total pressure - partial   pressure  of  oxygen

Here total pressure = 757.3 torr

Partial pressure of oxygen = 17 . 535 torr

Total pressure = 757 . 3 - 17 . 533

                        = 739.765 torr.

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6. The valence number of a metallic element x is 3. What is the chemical formula of its B. Nitride?

Answers

X has valency 3 and oxide ion has valency 2
So, the formula of oxide will be X
2

O
3

List the four quantum numbers

Answers

Answer: In atoms, there are a total of four quantum numbers: the principal quantum number (n), the orbital angular momentum quantum number (l), the magnetic quantum number (ml), and the electron spin quantum number (ms).

Answer:

(n)

(i)

(mı)

(ms) s is suppose to be smaller than the m

Explanation:

the principal quantum number (n)

the orbital angular momentum quantum number (I)

the magnetic quantum number (ml)

the electronic spin quantum number (ms)

An aqueous solution was prepared by dissolving 266.07 g of AgNO3 ( 169.88 g/mol) in enough water to make a total volume of 250.0 ml. What is the molarity of the solution

Answers

Answer:

The correct answer is 6.265 M.

Explanation:

To find the molarity of the solution, we first must recall that molarity represents the number of moles of solute divided by the number of liters of solution. Thus, our first step should be to convert the solute amount in grams to moles, using the given molar mass.

266.07 g * (1 mol/169.88 g) = 1.5662 mol

Now, we can find the molarity using the following formula:

Molarity = moles solute/liters solution

M = 1.5662 mol/0.25 L

M = 6.265 M

Therefore, the molarity of the solution is 6.265 M.

Hope this helps!

Acid hydrolysis of N-methylbutyramide in water and hydrochloric acid with heat produces______________________________.
a. Butyric acid and methylammonium chloride.
b. Butanoic acid and ammonium chloride.
c. Butanoate and methylamine.

Answers

Answer:

A- Butyric acid and methylammonium chloride.

Explanation:

using the formula F=ma, what force is required to accelerate a car weighing 642 kg at 13 m/s2


REALLY NEED HELP RN
HELP ME ?
PLEASE!??

Answers

Answer:

8,346 kmxm/s2

Explanation:

this is physics not chem but you just multiply 13 by 642 to get 8,346. also I'm sorry but it's easy

Give reason. When the tip of a plant is cut, it does not grow tall.

Answers

Answer: The growth of the plant decides on the presence of plant hormone, auxin which develops in the roots and shoots. Auxins change the rate of elongation in plant cells, controlling how long they become. So, if the tips are removed, there is no auxin made and growth of the plant stops.

a meter is defined as 100. cm. How many significant digits are there in the value

Answers

Answer:

3 significant figure

Explanation:

Trailing zeros in a number are significant ONLY is the number contains a decimal point.

So if it was 100cm with out the decimal point would only have 1 significant figure.

milk is heterogeneous mixture why​

Answers

Answer:

Milk is essentially a colloidal dispersion of fat in water. ... However, the fact remains that the fat and water components cannot be mixed together from a solution. There are therefore, two distinct immiscible liquid phase's present, which is why it is a heterogeneous mixture.

If there is a name/surname you can't make out due to a speaker's manner of speech, what are you supposed to do?

Answers

We can call a person by the word gentleman and Sir or from his/her real name.

If there is a name/surname you can't make out due to a speaker's manner of speech then I will call him gentleman or Sir or I will ask him his real name. Gentleman is a word that is used for noble person and Sir word is also used in order to give someone respect.

Call a person with his real name is also comes under the manner of speech so we can conclude that we can call a person by the word gentleman and Sir or from his/her real name.

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What are the two elements sand is made of? *

Answers

Answer:

tiny crystals of the mineral quartz, which is made out of silica and oxygen

Well, much of the world's sand is made out of the same stuff, tiny crystals of the mineral quartz, which is made out of silica and oxygen, the two most common elements in Earth's crust.

Which example accurately describes a solution? (1 point)

Nonpolar oil molecules dissolve in water, which is polar.

Polar sugar molecules dissolve in water, which is polar.

Nonpolar fat molecules dissolve in water, which is polar.

Polar sugar molecules dissolve in oil, which is nonpolar.

Answers

The example which accurately describes a solution is; Polar sugar molecules dissolve in water, which is polar.

According to the question:

We are required to determine Which example accurately describes a solution.

The formation of a solution requires that the solvent and solute be of the same polarity.

In essence, the example which accurately describes a solution is; Polar sugar molecules dissolve in water, which is polar.

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Answer:

Polar sugar molecules dissolve in water, which is polar.

Explanation:

I did the Exam and got it right!

If 9 moles of P203 are formed, how many
moles of O2 reacted?

Answers

9 x 3 = 27
27 moles of O reacted
27 / 2 = 13.5 O2 reacted
round up to 14 moles of O2

Draw and Name the Cis- isomer for the following compound:
CH3 - CH = CH - CH2 - CH3

Answers

Answer:

Cis-2-pentene or Z-2-pentene

Which functional group does the molecule below have?

Answers

Answer:

B

Explanation:

We can see here that the functional group that the molecule have is: B. Carbonyl

What is a functional group?

A functional group is a specific group of atoms or bonds within a molecule that is responsible for the characteristic chemical reactions and properties of that molecule. Functional groups are the parts of organic molecules that determine their reactivity and the types of chemical reactions they can undergo.

In organic chemistry, functional groups play a crucial role in understanding the structure and behavior of molecules. Different functional groups confer distinct properties to molecules, influencing their physical properties, solubility, acidity or basicity, and interactions with other molecules.

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What is the percentage of nitrogen in ammonium chloride (NH4Cl)?

Answers

Answer:

25%

Explanation:

Ammonium Chloride NH4CI Fertilizer-grade NH4Cl usually contains 25% N. About two-thirds of the world capacity for manufacture of this material is located in Japan, with the remaining one-third situated in India and China.

A 0.1 M NaCl solution and a 0.2 M glucose solution are separated by a membrane that is impermeable to these solutes but is permeable to water. What will happen

Answers

nothing will happen

if you calculate the water potiential for both solutions

you get 2(0.1)(R)(T) and 1(0.2)(R)(T)

which is the same thing, so its isotonic.

Electrical bonding refunding quick check!!


A team wants to understand the effects of molecular weight on boiling point. The team has access to five substances with
different molecular weights and the time to measure 50 boiling points. How can the team make the best use of the laboratory
testing time? (1 point)

O by taking 10 measurements of each of the five liquids and using the highest value from each set
O by taking 10 measurements of each of the five liquids and finding an average
O by taking measurements of the liquids one at a time, making sure that the correct results are achieved before
moving on to another liquid
O by taking one measurement of each liquid and then working to improve the least certain liquid in the group

Answers

Answer:

1. More data should be collected to get a more reliable average

2. A boiling point at 1.5 atmospheres could be predicted fairly well

3. The actual boiling point is probably between 34 C and 40 C

4. By taking 10 measurements of each of the five liquids and finding an average

5. The thermometer being used might need to be recalibrated

Explanation:

Took the quick check

I NEED HELP ASAP !!!!

Answers

Answer:

5)A &D 6)B

Explanation:

Mass of Fe is 55.845 u

Mass of Cl is 35.453 u

And their sum is 91.298 u

What is the molarity of the nitric acid solution if 20.5 mL of a 0.125 M lithium hydroxide solution are needed to titrate a 25.0 mL sample of the nitric acid solution

Answers

Answer:: We're asked to find the molar concentration of the NaCl solution given some titration data.

Explanation:

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Three plants are grown in the same environmental conditions with equal sunlight, water, and space to grow. One plant grew to have a purple flower while the other two grew white flowers. What is the most likely conclusion that can be made for the change in flower color?(1 point)Genetic factors caused environmental changes that caused the differences in flower color.Genetic factors caused the differences in flower color.Environmental factors caused a genetic mutation that caused the differences in flower color.Environmental conditions caused the differences in flower color. a full stretching session should take between __________. How does the excerpt help you to understandDavid as a ruler of the Israelites how long does it take for intermittent fasting to work What impact does the word "nomad," as used in the following sentence, have on the overall meaning of the text? "i knew i would never again fully be a part of my reservation. I knew i was going to be a nomad. ". Item 9Golden Daysby Lizzie Lawson There are days of summer sunshine, Of warm and sunny weather, When the hedge is full of hawthorn And hills are glad with heather. There are days of silent sadness, Of frost, and snow, and rain, When we fear that summer's gladness Will never come again. And now our songs are minor key, And now in merry tune; The windward side will change to lee, And January to June. Day and night the sun is shining, Though he may hide his head; Each cloud has a silver lining, The flowers are asleep not dead. Every day may have its playtime Made bright by cheerful lays; And life be one long Maytime, A year of golden days.Read the theme.Life, like nature, has pleasant and unpleasant moments.How does this theme develop over the course of "Golden Days"?Happiness is like the warmth of summer, and sadness is like the coldness of winter.The playtime of spring helps people feel alive and excited again after a long winter.The seasons are all rewarding and pleasant in their own unique ways.Nature and life are both unpredictable, especially during winter and summer months. Holden is trying to determine the velocity of his race car. He went 20 meters east, turned around, and went 40 meters west. His car was 20 meters from the starting line. This took 5 seconds. What is the cars average velocity?4 m/s east 4 m/s west12 m/s west12 m/s east A flying disc has a 7 3/4 inch radius. What is its approximate circumference,rounded to the nearest inch? A stimulant speeds up body functionsQuestion 5 options: a) True b) False ABCD is a parallelogram. What is the measure of ACD? 7.The transformation described below adds 1 to the x-coordinate and doubles the y-coordinate of any given point.(x,y) (x + 1, 2y)2What is the effect of this transformation on distance and angle measure?A. It preserves angle measure but does not preserve distance.B. It preserves neither distance nor angle measure.C. It preserves both distance and angle measure.DIt preserves distance but does not preserve angle measure. Highlighter pens cost $3.86 per set at an office supply store. Which equation can be used to determine the price, P, of n sets of these pens 1 kg ball has eight joules of kinetic energy. what is its speed? Is the subject complement in the sentence a noun, pronoun, or adjective?The grandfather clock in the attic has been silent for many years.a: nounb: pronounc: adjective Why are judges called the great jurists in common law? what theme is developed in the poem bush medicine by konai helu thaman Help help help help help Multiply.[3914][(0.1)(28)]What is the product? Check image for question Police response time to an emergency call is the difference between the time the call is first received by the dispatcher and the time a patrol car radios that it has arrived at the scene. Over a long period of time, it has been determined that the police response time has a normal distribution with a mean of 6.4 minutes and a standard deviation of 1.7 minutes. For a randomly received emergency call, find the following probabilities. a) between 5 and 10 min.b) less than 5 min.c) more than 10 min.