Which solution is the most concentrated?
2.0 mL of 10 M H2SO4, where H2SO4 has a molar mass of 98 g/mol
5.0 mL of 1.0 M PbSO4, where PbSO4 has a molar mass of 303 g/mol
2.0 mL of 10.5 M H2O2, where H2O2 has a molar mass of 34 g/mol
100 mL of 10 M NaCl, where NaCl has a molar mass of 58 g/mol

Answer:

The pattern of decay emission is visualized on X-ray film by auto-radiography.

Explanation:

The image on the x-ray are auto-radiography or the nuclear emission that has been produced as a result of the decay emission because of the gamma particles or the beta particles which comes from a radioactive substance.  These auto-radiography are available as the digital image as a result of recent development of gas detectors or because of the rare earth phosphor imaging system. Some of the can be studied microscopically for silver granules this method is called as micro- auto-radiography.

Answer: the pattern of hybridization

Explanation:

did it

The correct order for the first three steps of the scientific method is:D. State the question, form a hypothesis, conduct an experiment.

Here is a step-by-step explanation:

1. State the question: This is the first step in the scientific method. It involves identifying a problem or question that you want to investigate. It is important to clearly define the question you want to answer through your experiment.

2. Form a hypothesis: After stating the question, you need to come up with a hypothesis. A hypothesis is an educated guess or prediction that explains the relationship between the variables being studied. It is usually stated as an "if-then" statement, where you propose that if a certain condition is met, then a specific outcome will occur.

3. Conduct an experiment: Once you have a hypothesis, you can design and carry out an experiment to test it. An experiment involves systematically manipulating and controlling variables to observe their effects and gather data. It is important to carefully plan and conduct the experiment to ensure reliable and valid results.

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Answer:

Ex1 = 4.3 moles

Explanation:

for Ex 1

 ** Number of mole = Mass (g) / Molecular weight ' Mw'  (g/mole)

for a = NaCl , first you must be calculate Mw = look to periodic table

Atomic weight for Na is 22.9 = 23 g and for Cl is 35.45 = 35 g

so Mw for NaCl = 23+35 = 58 g/mole

so Number of Moles for NaCl 250 g is

Number of Moles = 250 / 58 = 4.3 moles

do same for others ...

good luck ..

Answer:

Ex1. a) n NaCl = 4.277 mol NaCl

b) n KNO2 = 2.938 mol KNO2

c) n H2O2 = 7.349 mol H2O2

d) n KHSO3 = 2.080 mol KHSO3

Ex2. a) 2.31 E22 particles contained in 1.5 g K

b) 1.77 E22 particles contained in 0.470 g O

c) 2.332 E21 particles contained in 0.555 g AgCl

Ex3. molecules C2H5OH = 2.065 E24 molecules contained in 200 mL

Explanation:

Ex1.   n = mass (m) / molecular weight (Mw)

a) Mw NaCl = 22.989 + 35.453 = 58.442 g/mol

⇒ n NaCl = (250 g NaCl)/(58.442 g/mol) = 4.277 mol NaCl

b) Mw KNO2 = 39.0983 + 14.0067 + (2)15.9994 = 85.104 g/mol

⇒ n KNO2 = (250 g KNO2)/(85.104 g/mol) = 2.938 mol KNO2

c) Mw H2O2 = (2)(1.00794) + (2)15.9994 = 34.015 g/mol

⇒ n H2O2 = (250 g H2O)/(34.015 g/mol) = 7.349 mol H2O

d) Mw KHSO3 = 39.0983 + 1.00794 + 32.065 + 15.9994(3) = 120.169 g/mol

⇒ n KHSO3 = (250 g KHSO3)/(120.169 g/mol) = 2.080 mol KHSO3

Ex2.  n =  (m) / (Mw)

∴ 1 mol ≡ 6.022 E 23 particles

a) Mw K = 39.0983 g/mol

⇒  K = (1.5 g K)×(mol/39.0983 g K)×(6.022 E23 part/mol) = 2.31 E22 particles

b) Mw O = 15.9994 g/mol

⇒ O = (0.470 g O)×(mol/15.9994 g O)×(6.022 E23 part/mol) = 1.77 E22 part

c) Mw AgCl = 107.8682 + 35.453 = 143.32 g/mol AgCl

⇒ AgCl = (0.555 g)×(mol/143.32 g)×(6.022 E23 part/mol) = 2.332 E21 part.

Ex3. ethyl alcohol ( C2H5OH)

∴ δ C2H5OH = 0.79 g/mL

∴ V = 200 mL

⇒ molecules C2H5OH = ?

∴ Mw C2H5OH = (2)12.0107 + (5)1.00794 + 15.9994 + 1.00794 = 46.068 g/mol

⇒ molecules C2H5OH = (200 mL)×(0.79 g/mL)×(mol/46.068 g)×(6.022 E23 molecules/mol)

⇒ molecules C2H5OH = 2.065 E24 molecules C2H5OH

Answer:

Air in a refrigeration system causes  All of the above problems.

Explanation:

The acid build up is basically seen when the circuit system comes in contact with air, moisture, more heat, various contaminants and also various impurities which enhances the chemical reaction helps in making of acid. Moisture is found when the warm air comes in contact with the cooling system inside the refrigerator. It basically occurs if the defrost condition not working properly.  Copper plating is the compressors metal parts that has been coated with the copper when this comes in contact with air leads to corrosion.

Answer & Explanation:

Take, for example, an apple tree. ... When an apple falls from the tree to the ground, its energy of position (stored as gravitational potential energy) is converted to kinetic energy, the energy of motion, as it falls. When the apple hits the ground, kinetic energy is transformed into heat energy.

Answer:

The percent yield is 42.52%.

Explanation:

Theoretical yield of beryllium chloride = 12.7 g

Actual yield of the beryllium chloride = 5.4 g

The formula used for the percent yield will be :

[tex]\text{Percent yield}=\frac{\text{Actual yield}}{\text{Theoretical yield}}\times 100[/tex]

Now put all the given values in this formula, we get:

[tex]\%(yield)=\frac{5.4 g}{12.7 g}\times 100=42.52\%[/tex]

The percent yield is 42.52%.

Answer:

15 g

Explanation:

Data given:

amount of  HF  = 153 mL  2.5 M HF

amount of Ca(OH)₂ = Excess

grams of CaF₂ = ?

Reaction Given:

                2HF + Ca(OH)₂ ------→ 2H₂O + CaF₂

Solution:

First we have to find number of moles of HF in 153 mL of 2.5 M HF

For this we will use following formula

               Molarity = moles of solute / liter of solution

Rearrange above equation

               moles of solute =  Molarity x liter of solution . . . . . (1)

Put values in above equation (1)

               moles of solute =  2.5 x 1 L

              moles of solute =  2.5

So,

we come to know that there are 2.5 moles of solute (HF) in 1 L of solution

Now how many moles of solute will be present in 153 ml of solution

Convert 153 mL to Liter

1000 mL = 1 L

153 mL = 153/1000 = 0.153 L

Apply Unity Formula

                       2.5 moles HF ≅ 1 L solution

                        X moles of HF ≅ 0.153 L solution

              moles of HF = 2.5 moles x 0.153 mL solution / 1 L solution

              moles of HF =  0.383 moles

Now Look at the reaction:

                     2HF + Ca(OH)₂ ------→ 2H₂O + CaF₂

                    2 mol                                          1 mol

From the reaction we come to know that 2 moles of HF gives 1 mole of CaF₂ then how many moles of CaF₂  will be produced from o.383 moles of HF

Apply Unity Formula

                       2 moles HF ≅ 1 mole of CaF₂

                       0.383 moles of HF ≅ X moles of CaF₂

              moles of CaF₂  = 0.383 moles x 1 mole / 2 mol

              moles of CaF₂ =  0.192 moles

Now we will find mass of 0.192 moles of  CaF₂

Formula will be used

          mass in grams = no. of moles x molar mass . . . . . . . (2)

molar mass of CaF₂ = 40 + 2(19)

molar mass of CaF₂ = 40 + 38 =  78 g/mol

Put values in eq. 2

        mass in grams = 0.192 x 78 g/mol

        mass in grams = 14.976 g

rounding the value

          mass in grams = 15 g

So,153 mL of 2.5 M HF is reacted with an excess of Ca(OH)₂ will produce 15 g of CaF₂.

Answer:

¹⁴₆C → ¹⁴₇N + ⁰₋₁e

Explanation:

Beta radiations:

Beta radiations are result from the beta decay in which electron is ejected. The neutron inside of the nucleus converted into the proton an thus emit the electron which is called β particle.

The mass of beta particle is smaller than the alpha particles.

They can travel in air in few meter distance.

These radiations can penetrate into the human skin.

The sheet of aluminium is used to block the beta radiation

⁴₆C → ¹⁴₇N + ⁰₋₁e

The beta radiations are emitted in this reaction. The one electron is ejected and neutron is converted into proton.

Answer: 14N7 + 1n0 = 14C6 + 1H1

Explanation: The question shows how atoms are being represented by the number of proton and the number of electron.

By simply taking mass balance for the left and right hand sides, that is:

14N+1n =?C+ 1H

?C = 15-1 =14

Also,

N7+n0 = C? + H1

C? = 7+0-1

C? =6

Hence,

?C? = 14C6

Answer: 1.D

2. A

3. D

Explanation:

Answer:

Changing direction is an example of a kind of acceleration

Explanation:

Acceleration is the "change of velocity" of an object concerning time. Acceleration being vector quantities, thus an object’s acceleration is the produce of orientation of the net force that has been acted on the object.  

Newton’s second law explains the magnitude of acceleration. An example is when a car travels in the straight line, it is accelerates in the direction of its travel. As the car turns the acceleration occurs in a new direction.  

Changing direction refers to acceleration, because it's about the change in velocity, which includes both speed and direction. So, if the direction changes but speed remains the same, there is still acceleration.

Changing direction is an example of a kind of acceleration. Acceleration is a vector quantity that is defined as the rate at which an object changes its velocity.

This is seen when an object changes its speed, direction, or both. For example, if you are driving a car and make a turn, even if your speed remains constant, you're experiencing acceleration because your direction is changing. Therefore, changing direction is associated with acceleration, not speed, velocity, or a constant rate.

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Answer:

They are found in various parts of the periodic table: the whole group of the noble gases (8A), as well as some elements of alkali metals (1A), groups 5A, 6A and 7A (halogens)

Explanation:

There are a total of 11 elements in the periodic table which are gases at room temperature and standard atmospheric pressure.

Considering the periodic table, there's first of all one prominent group, the noble gases, group 8A. The whole group contains gases, those are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn).

The remaining ones are also typically diatomic at room temperature. First of all, hydrogen (H) in group 1A. At room temperature, it exists as a diatomic gas, [tex]H_2[/tex].

We also have one diatomic gas in group 5A, this is nitrogen, [tex]N_2[/tex]. Another diatomic gas is found in group 6A, this is oxygen, [tex]O_2[/tex].

The final gases belong to the group of halogens, group 7A, those are also diatomic, fluorine ([tex]F_2[/tex]) and chlorine ([tex]Cl_2[/tex]).

Most regulatory signs are used to control the movement of traffic and they help the people to follow the rules and they are in the shape of vertical triangle

Explanation:

These sign are one that help to regulate the traffic for the traffic direction like the lane use, parking, turning, speed and in other special situation these signs are called as regulatory signs

They are most often in the shape of triangle with a red circle or a red dot in it indicating the signs and the direction in which they must move and the rule that they must not follow

Some of the examples are no right turn, no left turn and no U-turn

Answer:

c

Explanation:

Answer:

The correct answer is option C) When the atom absorbs photons, energy can only be emitted at specific frequencies creating a characteristic atomic emission spectra.

Explanation:

Emission spectrometry is a spectroscopic technique that analyzes the wavelengths of photons emitted by atoms or molecules during their transition from an excited state to a lower energy state. Each element emits a characteristic set of discrete wavelengths based on its electronic structure.

That is, each atom is capable of emitting or absorbing electromagnetic radiation, although only at some frequencies that are characteristic of each of the different chemical elements. If a certain element is stimulated in its gas phase, its atoms emit radiation at certain frequencies of the visible, which constitute its emission spectrum.

Expressed in other words, when a substance radiates with electromagnetic radiation the electrons choose the radiation of this continuous spectrum to produce jumps at higher levels (excited state).

When an electron jumps from its fundamental state to higher energy levels (excited state) and falls back to lower energy levels, the emission of a photon of a defined wavelength occurs that appears as a specific line or line in the spectrum broadcast. Electromagnetic radiation from radiation after passing through the substance is missing a series of lines that correspond to electronic jumps from the fundamental state to the excited state. It is what is called an absorption spectrum.

In summary, because each atom is capable of emitting or absorbing electromagnetic radiation, although only at some frequencies that are characteristic of each of the different chemical elements, the correct answer is option C) When the atom absorbs photons, energy can only be emitted at specific frequencies creating a characteristic atomic emission spectra.

Answer:

repelled

Explanation:

like charges repel one another

Answer : The correct option is, (C) 2-octene

Explanation :

Structural formula or bond-line formula : In the structural formula, the bonding and type of bonds which holds the atoms in molecule together are shown.

In bond-line formula, the lines are used between the bonded atoms and the atoms are also shown.

The basic rules for naming of organic compounds are :

First select the longest possible carbon chain.

For the number of carbon atom, we add prefix as 'meth' for 1, 'eth' for 2, 'prop' for 3, 'but' for 4, 'pent' for 5, 'hex' for 6, 'sept' for 7, 'oct' for 8, 'nona' for 9 and 'deca' for 10.

A suffix '-ane' is added at the end of the name of alkane.

If two of more similar alkyl groups are present, then the words 'di', 'tri' 'tetra' and so on are used to specify the number of times these alkyl groups appear in the chain.

In the given hydrocarbon, the longest possible carbon chain number is 8 that means we add prefix 'oct' and suffix '-ene' for double bond. So, the name of given molecule will be, 2-octene.

Hence, the name of the given molecule is, 2-octene.

Answer:

[ Na+ ]sln = 0.136 M

Explanation:

∴ mol Na2SO4 = ( 0.01728 L)×(0.078 mol/L) = 1.348 E-3 mol Na2SO4

⇒ mol Na+ = (1.348 E-3 mol Na2SO4)×(2 mol Na+/mol Na2SO4)

⇒ mol Na+ = 2.696 E-3 mol

∴ mol NaCl = (0.01130 L)×(0.20 mol/L) = 2.26 E-3 mol NaCl

⇒ mol Na+ = (2.26 E-3 mol NaCl)×(mol Na+/mol NaCl) = 2.26 E-3 mol Na+

⇒ total moles Na+ = 2.696 E-3 mol + 2.26 E-3 mol = 4.956 E-3 mol Na+

∴  total V sln = 17.28 mL + 11.30 mL + 7.84 mL = 36.42 mL = 0.03642 L sln

⇒ [ Na+ ]sln = (4.956 E-3 mol)/(0.03642 L) = 0.136 M

Answer:

Scientific knowledge can change because it is often examined and re-examined by new investigations and scientific argumentation but because of these frequent examinations, scientific knowledge becomes stronger, leading to its durability. Scientific knowledge is durable and robust, but open to change.

The importance of scientific knowledge changing lies in the fact that it represents the evolving nature of science, allowing us to deepen our understanding of the natural world, undergo paradigm shifts, and build cumulatively on previous knowledge.

It is important that scientific knowledge changes because science is a continuous, self-correcting process that develops our understanding of the natural world. Paradigm shifts, such as those identified by Thomas Kuhn, indicate radical changes in scientific thought that enable fresh understandings and advancements. For instance, rather than discarding Gregor Mendel's laws of inheritance upon learning how genes control traits, scientists expanded the framework, illustrating that knowledge is cumulative and subject to refinement as new discoveries emerge.

Debate and skepticism are inherent aspects of the scientific method and are crucial for validating and improving upon established ideas. This democratic nature ensures that the best data and theories prevail. Consequently, scientific progress is advanced as new findings are built upon the foundations laid by past research, allowing us to develop a larger, more accurate picture of our world and universe.

Furthermore, recognizing that scientific models are mental constructs subject to change, empowers us to remain flexible and receptive to new evidence while appreciating that some scientific knowledge can stand the test of time, providing continuity amid change.

Answer: it is easiest if you first find the percent of people present.  To do this, divide 1200/1500.  This equals 80%.  If there is 80% of students present, there needs to be 20% of students absent because it is out of 100% of students

Answer:

20%

Explanation:

Total number of students = 1500

Number of students present = 1200

Number of students absent = Total number of students - number of students present

Number of students absent = 1500 - 1200 =300

%number of students absent = 300 / 1500 * 100 = 20%

Answer:

f = 80  flutter/ second

T= 0.0125 sec

Explanation:

Given data:

Fluttering of wings = 4800 time per minute

Frequency of wings = ?

Period for one wing in sec = ?

Solution:

There are 60 seconds in one minute, thus frequency of wings

4800/60 = 80  flutter per second

Period:

T = 1/f

T = 1/80

T= 0.0125 sec

Answer:

flutters per second is 80 and the period is 0.013.

Explanation:

i just took the test.

Answer:

Plates sliding past each other cause friction and heat. Subducting plates melt into the mantle, and diverging plates create new crust material. Subducting plates, where one tectonic plate is being driven under another, are associated with volcanoes and earthquakes.

Explanation:

The length of a rectangle with a width of 4 inches and a length-to-width ratio of 3:2 is 6 inches.

If the ratio of the length of a rectangle to its width is 3 to 2, and if the width of the rectangle is 4 inches, we can set up a proportion to find the length. Using the ratio 3:2, we can write 3/2 = L/4, where L is the length of the rectangle we want to find. By cross-multiplying, we get 3 * 4 = 2 * L, which simplifies to 12 = 2L. Dividing both sides by 2, we find that L = 6 inches.

So, the length of the rectangle is 6 inches.

Answer:

Explanation:

Did you know? An ecosystem is defined as any community of living and non-living things that work together. Ecosystems do not have clear boundaries, and it may be difficult to see where one ecosystem ends and another begins. In order to understand what makes each ecosystem unique, we need to look at the biotic and abiotic factors within them. Biotic factors are all of the living organisms within an ecosystem. These may be plants, animals, fungi, and any other living things. Abiotic factors are all of the non-living things in an ecosystem.

Help this answer can help you :)

Sunlight, climate, soil, water, and air are the abiotic factors. Therefore, option D is correct.

Abiotic components, also known as abiotic factors, are non-living chemical and physical elements of the environment that have an impact on living organisms and the functioning of ecosystems. Biology is supported by abiotic factors and the phenomena associated with them.

Abiotic factors include sunlight, air, precipitation, minerals, and soil. These variables have a significant impact on species survival and reproduction in an ecosystem.

An abiotic factor is a non-living component of an ecosystem that influences its surroundings. Temperature, light, and water are some examples in a terrestrial ecosystem. Abiotic factors in a marine ecosystem include salinity and ocean currents.

Thus, option D is correct.

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Answer:

Low energy waves have a long wavelength.

Explanation:

Energy of wave is directly related to  the frequency while it is inversely proportional to the wavelength.

If any wave have high energy it will have high frequency and smaller wavelength.

If the wave have lower energy then it will have lower frequency and higher wavelength.

Mathematical relationship:

E = h. f

E = h. c/λ

E= energy

h = planck's constant

f = frequency

c = speed of light

λ = wavelength

Answer:

D)All of the above

Explanation:

The dot structure for magnesium illustrates it losing its two outermost electrons when forming compounds like MgO, indicating its tendency to achieve stability. Magnesium can participate in more complex bonding geometries, such as 4-coordinate (tetrahedral), but in the simple formation of magnesium oxide, the focus is on the ionic bond and electron transfer.

The question asks for the dot structure for magnesium, focusing specifically on its bonding and coordination number in chemical compounds. Magnesium, with an atomic number of 12, has its electrons arranged in a [Ne]3s² configuration. This means magnesium has two electrons in its outermost shell that it tends to lose to achieve a stable electronic arrangement, resembling the nearest noble gas, neon. When forming ionic compounds like magnesium oxide (MgO), magnesium donates its two outermost electrons to oxygen, resulting in a structure where magnesium has no dots around its symbol, indicating it has lost its valence electrons.

Magnesium's tendency to form compounds with specific geometries, either 4-coordinate (tetrahedral) or 6-coordinate (octahedral), highlights its versatility in chemical bonding. However, in the simpler case of forming ionic bonds, as in MgO, the focus is primarily on the transfer of electrons rather than the arrangement in complex geometries. The transformation into MgO exemplifies this process, underscoring the ionic character of the bond formed between magnesium and oxygen, a key concept in understanding magnesium's chemical behavior.

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It's an atom with the same number of protons but a different number of neutrons and thus, a different mass number.

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Explanation: Every atom/element is defined by its protons so if it has 1 atom it's hydrogen no matter what, if it has 2 protons it's helium no matter what and so on. If you know the number or protons, you know the element.

You can change the number of neutrons in the nucleus and you'll get isotopes. So atoms that have different numbers of neutrons are isotopes of each other. However, the element is the same but one is going to be a little bit heavier or lighter than another.

So, isotopes are different versions of an element.

Answer:

The number of chlorine atoms present in [tex]6.02 \times 10^{23}[/tex] units of gold III chloride is [tex]18.066 \times 10^{23}[/tex]

Explanation:

Formula of Gold (III) chloride: [tex]AuCl_{3}[/tex]

Avogadro Number : Number of particles present in one mole of a substance.

[tex]{N_{0}} =6.022 \times 10^{23}[/tex]

Using,

[tex]n(moles)=\frac{Given\ number\ of\ particles}{N_{0}}[/tex]

[tex]n =\frac{6.02\times 10^{23}}{6.022\times 10^{23}}[/tex]

= 1 mole(0.9999 , nearly equal to 1 )

The given Gold III chloride sample is 1 mole in amount.

[tex]6.022 \times 10^{23}[/tex]  = 1 mole of [tex]AuCl_{3}[/tex]

In this Sample,

1 mole of [tex]AuCl_{3}[/tex] will give = 3 mole of Chlorine atoms

1 mole of Cl contain = [tex]6.022 \times 10^{23}[/tex]

3 mole of Cl contain = [tex]6.022 \times 10^{23}\times 3[/tex]

3 mole of Cl contain =[tex]18.066 \times 10^{23}[/tex]

So,

The number of chlorine atoms present in [tex]6.02 \times 10^{23}[/tex] units of gold III chloride is [tex]18.066 \times 10^{23}[/tex]

Answer:

[tex]2s^2 2p^2[/tex]

Explanation:

Group 4A contains a total of 4 electrons for each atom in their valence shell. Filling the orbital diagram, let's say, for carbon, notice that when we start with period 2, we have two elements in the s-block, that is, lithium and beryllium. They correspond to the two s electrons that belong to the valence shell of carbon.

Moving on, we have boron and carbon, the remaining 2 electrons. Now, starting with boron, we're in the p-block.

That said, looking at the second period, the electron configuration for the valence shell of a group 4A element would be:

[tex]2s^2 2p^2[/tex]

Answer:

The periodic table is a table representing all the elements found in nature.

Following are the limitations of the modern periodic table:

Final answer:

At equilibrium, the forward reaction rate equals the reverse reaction rate, indicating a dynamic balance where the concentrations of reactants and products remain constant.So,option d. The forward reaction rate is equal to the reverse reaction rate is correct.

Explanation:

When a reaction is at equilibrium, the forward reaction rate is equal to the reverse reaction rate. This state is achieved when the rate of the forward reaction decreases and becomes constant while, simultaneously, the rate of the reverse reaction increases and becomes constant, reaching a point where both rates are equal. This equilibrium indicates that the concentrations of reactants and products remain constant over time, illustrating a dynamic balance between the forward and reverse processes.