Which of the following indicates that an exothermic reaction has taken place?

A. a change in color

B. release of heat and/or light energy

C. cooling of the surroundings

D. absorption of heat by the reaction ...?

The molar concentration of the solution is 1.55 mol/L.

1. Convert grams to moles.

[tex]\text{Moles of NaOH} = 15.5 \text{g NaOH} \times \frac{\text{1 mol NaOH}}{\text{40.00 g NaOH}} = \text{0.3875 mol NaOH}\\[/tex]

2. Convert millilitres to litres

[tex]V = 250.0 \text{mL} \times \frac{\text{1 L}}{\text{1000 mL}} = \text{0.2500 L}\\[/tex]

3. Calculate the molar concentration (c)

[tex]c = \frac{\text{moles}}{\text{litres}} = \frac{\text{0.2875 mol}}{\text{0.2500 L}} = \textbf{1.55 mol/L}[/tex]

Molarity of solution is 1.5501

Given data:

Molarity of NaOH = ?

Volume of solution = 250 ml

Mass of solute = 15.5 grams

Solution:

Formula:

Molarity = Mass of solute/Molar mass of solute * 1/volume of solution in liters.

First convert volume into Liters = 250/1000 =0.25 L

Now put the values in formula:

Molarity of NaOH = 15.5/39.997 * 1/0.25

                              = 1.5501

                                         Molarity of NaOH      =  1.55011

Answer:  1.0 kilograms.

Explanation:

One kilogram is equal to a thousand grams.

Supposing x to be the number of kilograms equal to one thousand and eight grams, we can write it as:

1 kg = 1000 grams

x kg = 1008 grams

To solve for x, we can simply divide 1008 grams by 1000 thousand grams to get the answer.

x = 1008 / 1000

x = 1.008

Rounding this value to the nearest tenth, it will become 1.0 kilograms.

1,008 grams is equivalent to 1.008 kilograms, and when rounded to the nearest tenth of a kilogram, it is 1.0 kilogram.

To find out how many kilograms 1,008 grams is, we need to convert grams to kilograms. We know that 1 kilogram is equal to 1,000 grams. Therefore, we need to divide the number of grams by 1,000 to convert to kilograms. For 1,008 grams, the calculation is as follows:

1,008 grams / 1,000 = 1.008 kilograms

When rounding to the nearest tenth of a kilogram, we get 1.0 kilograms because the hundredth place is less than 5.

So, the answer is that 1,008 grams is equivalent to 1.0 kilogram when rounded to the nearest tenth.

Answer : The correct formula of the compound is, [tex]N_2O_5[/tex]

Explanation :

Dinitrogen pentoxide  is a covalent compound in which both the elements nitrogen and oxygen are non-metals.

The formula of covalent compound is given by:

So, the formula of given compound is, [tex]N_2O_5[/tex]

The answer to problem is [He] 2s1. Hope it helps

Your answer is [He] 2s1

Hope that helps :)

Answer: Groundwater that forms caves because it is slightly acidic.

Explanation:

The water under the ground present inside the cracks and spaces in sand, soil and rocks is called ground water.

When ground water moves through the soil it results in the formation of acid. Further, this acid helps minerals to get dissolve. These minerals get deposited on other places as well.

This process of deposition and erosion helps in the formation of caves.

Thus, it can be concluded that groundwater that forms caves because it is slightly acidic.

Pressure is the amount of force applied per unit area perpendicular to the surface, represented by the formula P = F/A, with P being pressure, F the force, and A the area; pressure is measured in pascals (Pa).

The concept in question refers to pressure, which is a fundamental idea in the field of physics. Pressure is defined as the force applied per unit area that is perpendicular to the force. The equation for calculating pressure is P = F/A, where P stands for pressure, F represents the force applied, and A denotes the area over which the force is distributed.

Note that while force is a vector quantity, meaning it has both magnitude and direction, pressure is a scalar quantity. This is because pressure is proportional to the magnitude of the force acting perpendicular to the surface and does not have a direction associated with it. The standard unit for measuring pressure is the pascal (Pa), which is named after the renowned French mathematician and physicist Blaise Pascal.

The formula of pentaphosphorus tetraoxide is P₅O₄

As per the convention of naming chemical compounds - the Prefix names are used for naming covalent compounds.

The prefix 'penta' means '5', so we use 5 as subscript for P.

The prefix 'tetra' means '4', so we use 4 as subscript for O.

Therefore the formula of pentaphosphorus tetraoxide is P₅O₄

Hey there!

Molar mass NaCl = 58.44 g/mol

Number of moles

n =  mass of solute / molar mass

n = 59.76 / 58.44

n = 1.0225 moles of NaCl

Volume in liters:

270 mL / 1000 => 0.27 L

Therefore:

M = number of moles / volume ( L )

M = 1.0225 / 0.27

= 3.78 M

Hope that helps!

Si, silicon. The oxide is SiO2, silicon dioxide. ...

Na, sodium. The oxide is Na2O. It is introduced as a white powder called soda ash.

Ca, calcium. The oxide is CaO. ...

Pb, lead. The oxide is PbO. ...

K, potassium.

The correct answer is option A and B

About 300 B.C., Aristarchus suggested that the sun was at the center of the universe because a) the brightness of the planets would change and b) the planets appeared to move among the constellations.

18 centuries before  Copernicus, Aristarchus predicted that  all planets orbit the sun. In other words, he suggested the Solar System is heliocentric.

Answer:

the answer is A And B

Explanation:

just took the test

Answer:

B.6

Explanation:

Out of the 25 elements found in living things, 19 of them can be found in some organisms but not all.

There are 25 elements that living things on Earth need to survive. Out of all these 25 however, only 6 are needed by all living organisms universally. They include:

In conclusion, this means that 19 elements can be found in some living things but not all of them while 6 can be found in all of them.

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C. Gases only

Gases are the state of matter that has no definite shape and volume while liquids have no definite shape but have definite volume and solids have both definite shape and definite volume. so the correct option is "C".

all of above ! they are involved in all thee mentioned here

1) The answer is: C.  heterogeneous mixture.

Heterogeneous mixture is not uniform in composition.

This substance is not element or compound, because different components could be observed in the substance.  

Pure substance is made of only one type of atom (element) or only one type of molecule (compound), mixtures and solutions are made from two or more types of pure substances.

For example, aluminium is an element and ammonia is compound.

This substance is not a homogeneous mixture, because different samples of the substance appeared to have different proportions of the components.  

2) The answer is: A. It represents the beliefs of most scientists.

Consensus is general agreement, but not necessarily unanimity.

Consensus is achieved through communication at conferences, the publication process, replication and peer review.

For example, 97 percente of scienties agree that climate warming trends over the past century are extremely likely due to human activities.

According to ideal gas equation, there are 1.55 moles in the sample of gas.

To calculate the number of moles in a sample of gas, we can use the Ideal Gas Law equation: [tex]PV=nRT[/tex] where P is the pressure of the gas, V is its volume, n is the number of moles, R is the gas constant, and T is the temperature in Kelvin.

We can rearrange the Ideal Gas Law equation to solve for n:

[tex]n=\dfrac{PV}{RT}[/tex]

Given:

V = 27.5 L

T = 302 K

P = 1.40 atm

We can use the gas constant, R, which is 0.0821 L·atm/mol·K.

Plugging in the values:

[tex]n=\dfrac{1.40}{0.0821}[/tex]×[tex]\dfrac{27.5}{302}[/tex]

=1.55 moles

Therefore, the number of moles in the sample of gas is 1.55 moles. Hence, option C is correct.

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The density of crystal is 2.65 g / mL

we know that

Density = Mass / Volume

So volume occupied = Mass / density

Mass of crystal = 4.46 g

So volume occupied by crystal = 4.46 / 2.65 = 1.68 mL

As the graduated cylinder contains water upto 25.0 mL

So if we immerse the crystal in that cylinder the water level will rise to 25+1.68 = 26.68mL

so the new read will be 26. 68 mL

To calculate the volume of the unknown crystal, subtract the initial volume of water from the final volume, assuming the crystal is insoluble. Use the formula: Volume of Crystal = Final Volume - Initial Volume (water). Substitute the given values to find the volume of the crystal.

The volume of the unknown crystal can be calculated using the given density and the mass of the sample added to the graduated cylinder.

First, we need to calculate the volume of water in the graduated cylinder by subtracting the initial volume (25.0 ml) from the final volume. Assuming the unknown crystal is insoluble in water, the total volume will be the sum of the water volume and the volume of the crystal.

The final volume can be calculated using the formula:

Final Volume = Initial Volume (water) + Volume of Crystal

By rearranging the formula, we can solve for the volume of the crystal

Volume of Crystal = Final Volume - Initial Volume (water)

Substituting the given values, the volume of the crystal can be calculated.

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Q: The recommended daily allowance of selenium in your diet is 6.97x10-7 mole. How many atoms of selenium is this?

                  4.19 × 10¹⁷ Se Atoms

                     As we know that 1 mole of any substance contains exactly 6.022 × 10²³ particles which is also called as Avogadro's Number. So in order to calculate the number of particles (atoms) contained by 6.97 × 10⁻⁷ moles of Se, we will use following relation,

           Moles  =  Number of Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of Atoms,

           Number of Atoms  =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

Putting values,

           Number of Atoms  =  6.97 × 10⁻⁷ mol × 6.022 × 10²³ Atoms.mol⁻¹

           Number of Atoms  =  4.19 × 10¹⁷ Atoms

++++++++++++++++++++++++++++++++++++++++++++++++++

Q: A bracelet containing 0.200 mol metal is 75% gold. How many atoms of gold are in the bracelet?

                  9.033 × 10²² Atoms of Gold

                     As we know that 1 mole of any substance contains exactly 6.022 × 10²³ particles which is also called as Avogadro's Number. So in order to calculate the number of particles (atoms) contained by 0.200 moles of Au, we will use following relation,

           Moles  =  Number of Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of Atoms,

           Number of Atoms  =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

Putting values,

           Number of Atoms  =  0.200 mol × 6.022 × 10²³ Atoms.mol⁻¹

           Number of Atoms  =  1.20 × 10²³ Atoms

For 75%,

           Number of Atoms  =  1.20 × 10²³ Atoms × 0.75

           Number of Atoms  =  9.033 × 10²² Atoms of Gold

++++++++++++++++++++++++++++++++++++++++++++++++++

Q: Which has more atoms, 10.0 g C or 10.0 g of Ca? How many atoms does each contain?

               Carbon has greater number of Atoms.

Data Given:

                 Mass of Carbon =  10 g

                 M.Mass of Carbon  =  12.01 g.mol⁻¹

                 Mass of Calcium =  10 g

                 M.Mass of Calcium  =  40.08 g.mol⁻¹

Step 1: Calculate Moles of Carbon as,

                 Moles  =  Mass ÷ M.Mass

Putting values,

                 Moles  =  10 g ÷ 12.01 g.mol⁻¹

                 Moles  =  0.8326 mol

Step 2: Calculate number of Carbon atoms,

As 1 mole of any substance contains 6.022 × 10²³ particles (Avogadro's Number) then the relation for Moles and Number of Carbon atoms can be written as,

                 Moles  =  Number of C Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of C atoms,

                 Number of C atoms  =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

Putting value of moles,

                 Number of C atoms  =  0.8326 mol × 6.022 × 10²³ Atoms.mol⁻¹

                 Number of C atoms =  5.01 × 10²³ C atoms

Step 3: Calculate Moles of Calcium as,

                 Moles  =  Mass ÷ M.Mass

Putting values,

                 Moles  =  10 g ÷ 40.08 g.mol⁻¹

                 Moles  =  0.25 mol

Step 4: Calculate number of Calcium atoms,

As 1 mole of any substance contains 6.022 × 10²³ particles (Avogadro's Number) then the relation for Moles and Number of Calcium atoms can be written as,

                 Moles  =  Number of Ca Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of Ca atoms,

                 Number of Ca atoms  =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

Putting value of moles,

                 Number of Ca atoms  =  0.25 mol × 6.022 × 10²³ Atoms.mol⁻¹

                 Number of Ca atoms =  1.50 × 10²³ C atoms

++++++++++++++++++++++++++++++++++++++++++++++++++

Q: A mixture contains 0.250 mol Fe and 1.20 g C. What is the total number of atoms in the mixture?

                 2.10 × 10²³ Atoms in Mixture

Atoms in Fe:

                  As we know that 1 mole of any substance contains exactly 6.022 × 10²³ particles which is also called as Avogadro's Number. So in order to calculate the number of particles (atoms) contained by 0.25 moles of Fe, we will use following relation,

           Moles  =  Number of Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of Atoms,

           Number of Atoms =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

Putting values,

           Number of Molecules  =  0.25 mol × 6.022 × 10²³ Atoms.mol⁻¹

           Number of Molecules  =  1.50 × 10²³ Atoms of Fe

Atoms in C:

Step 1: Calculate Moles of Carbon as,

                 Moles  =  Mass ÷ M.Mass

Putting values,

                 Moles  =  1.20g ÷ 12.01 g.mol⁻¹

                 Moles  =  0.0999 mol

Step 2: Calculate number of Carbon atoms,

As 1 mole of any substance contains 6.022 × 10²³ particles (Avogadro's Number) then the relation for Moles and Number of Carbon atoms can be written as,

                 Moles  =  Number of C Atoms ÷ 6.022 × 10²³ Atoms.mol⁻¹

Solving for Number of C atoms,

                 Number of C atoms  =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

                 Number of C atoms  =  0.0999 × 6.022 × 10²³ Atoms.mol⁻¹

                 Number of C atoms  =  6.01 × 10²² C Atoms

Total Number of Atoms:

  =  6.01 × 10²² C Atoms + 1.50 × 10²³ Atoms of Fe

  =  2.10 × 10²³ Atoms in Mixture

Remaining answers are attached.

To solve this problem, we're going to have to use the equation: E=hv

This equation tells us that the energy of a particle of light (E), called a photon, is proportional to its frequency (v), by a constant factor (h). That constant (Planck's constant) we know to be 6.626 × 10^-34 J·s. So, we can plug in the frequency and Planck's constant to solve for the energy (E).

E=( 6.626 × 10^-34 J·s)(7.29 × 10^14 hz)

E= 4.830354 × 10^-19

Round to 3 significant figures, and you're done!

E= 4.83 × 10^-19

Answer:

[tex]4.83\times 10^{-19} J[/tex] is the energy of exactly one photon of this light.

Explanation:

Frequency of the blue shade light = [tex]\nu =7.29\times 10^{14} Hz[/tex]

Energy of the photon is given by Planck's equation = E

[tex]E=h\nu[/tex]

h = Planck's constant = [tex]6.634\times 10^{-34} Js[/tex]

[tex]E=6.634\times 10^{-34} Js\times 7.29\times 10^{14} s^{-1}[/tex]

[tex]E=4.83\times 10^{-19} J[/tex]

[tex]4.83\times 10^{-19} J[/tex] is the energy of exactly one photon of this light.

Answer. C. The sample will mainly consist of granite.

Explanation:

Sample collected from was continental crust (a part crust) as the samples were from 60 km deep.  Continental crust ranges from 30 km to 70 km and this layer is mainly includes granite. This continental crusts is mainly responsible for formation of distinct land-forms like continents.

Statement A ,B and D informs us about the state and temperature of metals(iron) in core that is inner most  layer of the earth.

Pressure of argon = 546.8 kPa

Conversion factor: 1 atm = 101.325 kPa

Pressure of argon = 546.8 kPa x 1 atm/101.325 kPa = 5.4 atm

Moles of argon = 15.82

Volume of argon = 75.0 L

According to Ideal gas law,

PV = nRT

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

T = PV/nR = (5.4 atm x 75.0 L) / (15.82 x 0.0821 L.atm.mol⁻¹K⁻¹)

T = 311.82 K

Hence the temperature of the canister is 311.82 K.

Answer:

311.82

Explanation:

Answer

For this we use ideal gas equation which is:

P1V1 = P2V2

P1 = 1.10 atm

V1 = 326 ml

P2 = 1.90

V2 = ?

By rearranging the ideal gas equation:

V2 =  P1V1 ÷ P2

V2 = 1.10 × 326 ÷1.90

V2 = 358.6 ÷ 1.90

V2 = 188.7 ml

A mixture of charcoal, sand, sugar, and water is a heterogeneous mixture. Sugar can easily dissolve in water. Slightly heating the mixture will ensure all of the sugar is dissolved in the water. The mixture then can be filtered to separate out sugar solution from sand and charcoal. The mixture of sand and charcoal is washed several times with water and filtered so that no traces of sugar solution remain in the mixture. To the mixture containing sand and charcoal, water is added. Charcoal being lighter floats on the surface of water, whereas sand being heavy sinks to the bottom. The charcoal floating can be removed manually. After all the charcoal is removed, the mixture of sand and water is again filtered and the sand collected on filter paper is dried. Therefore, by using the above process sand can be separated out from a mixture of charcoal, sand, sugar, and water.

The process of separating sand from a mixture of charcoal, sand, sugar, and water involves sedimentation, decantation, filtration, and evaporation. Sedimentation and decantation help in separating sand and charcoal from sugar and water, filtration further separates sand and charcoal, and the remaining sugar and water can be separated through evaporation.

To separate sand from a mixture of charcoal, sand, sugar, and water, you can apply the process of filtration, sedimentation, and evaporation. First, sedimentation and decantation could be used to separate the sand and charcoal from the sugar and water. Given that sand and charcoal are insoluble, they will settle at the bottom of the container after some time, which can then be separated by gently pouring out the water and sugar solution. Then, you could proceed to use filtration to separate the charcoal and the sand. Due to their differences in size, the sand will be caught in the filter, while the charcoal will pass through. Lastly, the evaporation method can be used to separate the sugar from the water. When the mixture is heated, the water will evaporate, leaving the sugar behind.

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Answer:- Chlorine(Cl)

Explanations:- Electron affinity is the amount of energy released when an electron is added to an element in it's gaseous state. Electron affinity increases in a period on going left to right as the size of the element decreases and it's effective nuclear charge increases and this facilitate an element to accept the electron.

The elements mentioned here in the question belongs to the same group and out of these, chlorine is on the right most side and so it is correct choice.

Hence, Chlorine(Cl), because it is a halogen with a high effective nuclear charge is the correct choice.

The answer is: B) Chlorine (Cl), because it is a halogen with a high effective nuclear charge

Given data:

1 kilogram = 1,000 grams

how many kilograms is 1,216 grams?

Solution:

1000 grams = 1 kilogram

1 gram = 1/1000 kilograms

1216 grams = 1/1000 * 1216 = 1.216 kilograms.

                                                    Hence 1216 grams =  1.216 kilograms.

When solid copper(II) nitrate is dissolved in water, it breaks down into copper(II) ions and nitrate ions. This process is represented by the balanced chemical equation: Cu(NO3)2 (s) -> Cu^2+ (aq) + 2 NO3^- (aq).

When solid copper(II) nitrate, denoted as Cu(NO3)2, is put into water, it dissociates into its ions. The balanced chemical reaction is represented as follows:

Cu(NO3)2 (s) -> Cu^2+ (aq) + 2 NO3^- (aq)

Here, (s) stands for solid, while (aq) means aqueous, i.e., ions dissolved in water. Copper(II) nitrate breaks down into copper(II) ions (Cu^2+) and nitrate ions (NO3^-). Because copper(II) nitrate is a strong electrolyte, it dissociates completely in water, meaning there are no leftover solid particles floating in the solution, just a solution of the individual ions.

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A mixture is formed of two substances (molecules, elements, compounds, etc.) that are not chemically bonded. A compound is formed of two substances chemically joined together, so the answer is A.

Answer:

a. the substances in a compound are chemically joined in a fixed proportion.

Explanation:

A compound is defined as a pure substance that has more than one element. Compounds have a fixed composition. This means that a compound always has the same elements with equal percentages by mass. Meanwhile, a mixture is made up of two or more components that are mixed, but are not chemically combined.

Answer:

The quantity 10 m/s is the only vector quantity because it is a measurement that includes a direction.

Explanation:

Vector quantities are physical quantities with both magnitude (size) and direction. Examples of vectors include displacement, velocity, acceleration, force, momentum etc.

Time is a scalar quantity having only  size. So 10 s is not a vector. 10 m/s forwards is velocity because of the direction.

Final answer:

In Peter's experiment, the independent variable is the temperature of the water, and the dependent variable is the amount of salt that dissolves. The independent variable is what the experimenter changes, and the dependent variable is what is measured in response.

Explanation:

Understanding Variables in an Experiment

In Peter's experiment to determine how much salt will dissolve in water as the temperature is increased, the independent variable is the temperature of the water, which Peter is controlling or changing. The dependent variable is the amount of salt that dissolves in the water, which will change in response to the temperature alterations. It's important not to confuse the independent and dependent variables as one is the cause (independent) and the other is the effect (dependent).

Example from Another Experiment

In the provided example where a scientist is observing bacteria growth on different gels, the independent variable would be the type of gel (A or B) since this is what the scientist has changed. The dependent variable would be the amount of bacteria growth observed after 24 hours, as this is the outcome that depends on the type of gel used.