how many significant digits are in 38 students

The energy of a 4.25 × 10⁸ Hz wave is 2.816 × 10-²⁵ J.

The energy of a wave can be calculated by multiplying the frequency of the wave by Planck's constant as follows:

E = hf

Where;

According to this question, the frequency of a wave is given as 4.25 × 10⁸ Hz. The energy, if the Planck's constant is 6.626 × 10-³⁴ J/s, can be calculated as follows:

E = 6.626 × 10-³⁴ × 4.25 × 10⁸ Hz

E = 2.816 × 10-²⁵ J

Therefore, the energy of the wave is 2.816 × 10-²⁵ J.

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Answer:

great question

Explanation:

The concentration of the barium chloride solution is found to be 29.67 µmol/L.

The quantity of solute that has been dissolved in a certain volume of solvent or solution is measured by the solution's concentration. A solution that contains a lot of dissolved solute is said to be concentrated. If there is just a little amount of dissolved solute in a solution, it is said to be dilute.

Molarity is one of the most often used ways to represent the concentrations of solutions. It is the quantity of moles of solute dissolved in a solution that is one liter in size.

Given:

Barium chloride = 8.9 µmol

Volume = 300ml

To find:

Concentration of the solution = ?

Formula:

(Concentration of solute / volume of solution) x (1000mL/1L)

Calculations:

(8.9 / 300) x (1000/1)

= 29. 67 µmol/L

Result:

Therefore, the concentration of the barium chloride solution is 29.67 µmol/L

The complete question is:

A chemist prepares a solution of barium chloride by measuring out 8.9 μmol of barium chloride into a 300mL volumetric flask and filling the flask to the mark with water.

Calculate the concentration in μmol/L of the chemist's barium chloride solution. Round your answer to 2 significant digits.

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Using the ideal gas law equation, the gas pressure of helium becomes 0.6atm when the volume increases to 2[tex]m^3[/tex].

The general gas equation, often known as the ideal gas law, is the equation of state for a fictitious ideal gas. Although it has several restrictions, it is a decent approximation of the behaviour of numerous gases under various circumstances.

According to the ideal gas law, all gases have an equal number of molecules in an equal volume at a given temperature and pressure.

Ideal gas law:

PV = nRT

where,

P – Pressure

V – Volume

n – No. of moles

R – Gas constant

T - Time

Given:

V1 = 1[tex]m^3[/tex]

P1 = 1.2atm

V2 = 2[tex]m^3[/tex]

To find:

P2 = ?

Formula:

PV = nRT

Calculations:

PV/T = constant

P1V1/T1 = P2V2/T2

Since T1 = T2,

P1V1 = P2V2

1.2 x 1 = P2 x 2

P2 = 1.2 x 1 / 2

P2 = 0.6atm

Result:

The gas pressure of helium becomes 0.6atm when the balloon rises high and the volume increases to 2[tex]m^3[/tex].

The complete question is:

a helium gas balloon has a volume of 1[tex]m^3[/tex] and a gas pressure of 1.2atm. when it is high in the sky, the volume increases to 2[tex]m^3[/tex]. assuming the gas temperature does not change and there is no gas leakage, the gas pressure becomes _____atm.

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The following which is not a part of  Dalton atomic theory is the properties of atoms of the same elements can be different . Thus option B is correct.

Dalton has proposed his theory in three parts and each part stated that

The first portion of his theory asserts that all stuff is made up of indivisible atoms.

According to the second section of the theory, all atoms of a given element have the same mass and characteristics.

Compounds, according to the third section, are combinations of two or more different types of atoms.

Dalton has given three laws

Thus, the following which is not a part of  Dalton atomic theory is the properties of atoms of the same elements can be different . Thus option B is correct.

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Your question is incomplete, but your complete question was

which of the following is not a part of the ideas john dalton proposed in his model

A. All matter is composed of indivisible atoms.

B. The properties of atoms of the same element can be different.

C. Compounds form when atoms combine in whole number ratios.

D. An atom can neither be created nor destroyed.

Answer: L

Explanation:

The result of the replacement reaction  [tex]2Fe +3 CUSO_{4}[/tex] is [tex]2Fe(SO_{4} )_{3} + 3 Cu.[/tex]

[tex]2Fe +3 CUSO_{4} ----------- > 2Fe(SO_{4} )_{3} + 3 Cu.[/tex]

the above reaction is a Displacement reaction.

When an atom or group of atoms in a molecule is replaced by another atom, this is referred to as a displacement reaction. For instance, copper metal is displaced when iron is added to a solution of copper sulfate.

When one element replaces another in a compound, it causes a single displacement reaction. Neither metal nor a nonmetal may be used as a substitute for another metal. Only a more reactive component of the chemical it reacts with can take the place of the other component.

A new insoluble ionic compound is created by a precipitation reaction between two aqueous ionic compounds. The reaction between lead (II) nitrate and potassium iodide to produce (soluble) potassium nitrate and (insoluble) lead iodide is illustrated below.

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In the given electrolytic cell setup having molten zinc iodide as the electrolyte, reduction of zinc ions to gray coloured zinc occurs at the cathode, whereas iodide ions get oxidized to reddish-brown iodine at the anode.

An electrolytic cell is a type of electrochemical cell that uses an external source of electrical energy to power a chemical process that would not occur otherwise. This contrasts with a galvanic cell, which serves as a power source and the cornerstone of a battery.

Any apparatus in which electrical energy is changed into chemical energy or vice versa is an electrolytic cell. Such a cell normally consists of two electrodes, which can be metallic or electronic conductors, kept apart from one another and in contact with an electrolyte, which is commonly an ionic substance that has been dissolved or fused.

In the given setup, the molten zinc iodide is the electrolyte, and the half reactions occurring at the two electrodes of the electrolytic cell are:

Half reaction at the cathode:

[tex]Zn^{2+} (l) + 2e^- \rightarrow Zn (s)[/tex]

Half reaction at the anode:

[tex]2I^- (l) \rightarrow I_2 (s) + 2e^-[/tex]

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Sociology emerged in the early 1800s during a period of great social change when many academics and other educated citizens were fascinated by scientific discoveries social issues like the low high school graduation rate continue to interest sociologists today still important to understand and study society today because it gives students an understanding of the real world around them

Sociology is the of human society and social behavior and it started from 1800s during a period of great social change and studying social sciences gives students an understanding of the real world around them an students learn about places, cultures, and events around the world, what conspired to make them the way they are can make inferences about how the rest of the world works

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You are aware that the dissociation equilibrium for Manganese hydroxide appears as follows.

Mn(OH)2(s]⇌Mn2+(aq]+2OH−(aq]

The formula for the solubility product constant, Ksp, is Ksp=[Mn2+][OH].2

Rearrange to determine the hydroxide anions' concentration [OH]=Ksp/[Mn2+].

Enter your values to obtain

[OH−]=√1.0⋅10−110.1\s=√1.0⋅10−10=10−5M

As you are aware, you may calculate the solution's pOH using the concentration of hydroxide anions: pOH=log([OH]; pOH=log(105)=5

Lastly, make use of the correlation between pH and pOH at room temperature.

To determine the pH of the solution, use pH=145=9 + pOH.

As a result, the solution will be unsaturated for pH values lower than 9. The solution gets saturated and the magnesium hydroxide begins to precipitate after the pH of the solution reaches 9.

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Explanation:

from

c1v1=c2v2

c1=?

c2=0.250

v1=0.0225

V2=0.0100

c1×0.0225=0.250×0.0100

0.0225c1=0.0025

0.0225c1/0.0225=0.0025/0.225

c1=0.1111

36.78% (percent) of NaCl is present in the original sample mixture of NaCl and [tex]BaCl_2.2H_2O[/tex].

Given:

Original mass of sample mixture containing NaCl and [tex]BaCl_2.2H_2O[/tex] = 5.416g

After heating, the mass of the sample = 4.911g

To find:

Percent of NaCl in the sample = ?

Formula:

Percent of NaCl in the sample = (Mass of NaCl / Mass of original sample) x 100

Calculations:

Mass of water = 5.416 - 4.911 = 0.505g

Molar mass of [tex]BaCl_2[/tex] = 208.23g/mol

From the chemical formula - [tex]BaCl_2.2H_2O[/tex],

2 mols of [tex]H_2O[/tex] is attached with 1 mole of [tex]BaCl_2[/tex]

Therefore, with 208.23g of [tex]BaCl_2[/tex] , 36.03g of [tex]H_2O[/tex] is attached.

Therefore, 0.505g of [tex]H_2O[/tex] is attached with:

(208.23 / 36.03) x 0.505g of [tex]BaCl_2[/tex].

= 2.919g of [tex]BaCl_2[/tex]

Thus, Mass of NaCl in the original sample mixture = 4.911 - 2.919 = 1.992g

Percent of NaCl in the sample mixture = (1.992 / 5.416) x 100

Percent of NaCl in the sample mixture = 36.78 %

Result:

The percent of NaCl in the original sample mixture is 36.78%

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Two sublevels of the same principal energy level differ from each other through shape and size.

There are mainly 4 energy level s, p, d and f.

The s level has one orbital and one orbital have two electrons. So the maximum number of electron in s sublevel is 2.

The p level has three orbital and one orbital have two electrons. So the maximum number of electron in s sublevel is 6.

The d level has five orbital and one orbital have two electrons. So the maximum number of electron in s sublevel is 10.

The f level has 7 orbital and one orbital have two electrons. So the maximum number of electron in s sublevel is 14.

They may be differ in magnetic level.

Thus, we concluded that Two sublevels of the same principal energy level differ from each other through shape and size.

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The approximate pressure of 2 moles of helium in a 0.3m³ container at 300 K is 17000 Pa (option B).

The pressure of a gas can be calculated using the following formula;

PV = nRT

Where;

According to this question, 2 moles of helium in a 0.3m³ container is at 300K. The pressure can be calculated as follows:

P × 300 = 2 × 0.0821 × 300

300P = 49.26

P = 0.164 atm

This pressure value in Pascals is 16617.3, which is approximately 17000 Pascals.

Therefore, the pressure of a 2 moles of gas is 17,000 Pascals.

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The more vibrant purple color of the pre-partition solution suggests that the concentration of salicylic acid is higher in the pre-partition solution than in the post-partition solution because of the complex formed.

Ferric chloride (orange in color) interacts with phenolic hydroxy groups by creating a complex that has a strong purple color. The intensity of the color is proportional to the concentration of the phenol. Because salicylic acid contains a phenolic hydroxy group, its solution will also turn purple upon the addition of ferric chloride. If the pre-partition sample has a more vibrant color, then this means that the concentration of salicylic acid in it is significantly higher, which can then inform us on the effectiveness of the separation and partition process.  

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If you look at the molar mass of sodium on the periodic table, it is 22.99 grams/mole. If you look at the molar mass of chlorine on the periodic table, it is 35.45 grams/mole.

To find the molar mass of sodium chloride, we add these two values and that gets us 58.44 grams/mole.

Alright, so we know that 1 mole of NaCl is equal to 58.44 grams, so how many moles would 23.5 grams of NaCl be?

Now we just divide 23.5/58.44 and you get 0.40 moles of NaCl. (If you're confused on what value to put in the numerator, always put the value that you're interested in converting or calculating for.)

Answer: 0.40 moles

The empirical formula of the compound with 72.0 g of C. 18.0 g of H, and 28.0 g of N is C₃H₉N.

Empirical formula of a compound indicates the ratios of the various elements present in a compound, without regard to the actual numbers.

The empirical formula of a compound can be calculated as follows:

First, we divide by the atomic mass of each element as follows:

Next, we divide by the smallest mole as follows:

C = 6mol ÷ 2 = 3

H = 18 mol ÷ 2 = 9

N = 2mol ÷ 2 = 1

The empirical ratio is 3:9:1, hence, it can be said that the empirical formula is as follows: C₃H₉N.

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Answer:

Electromagnet

Explanation:

The motorcycle relies on energy to keep it going on and the energy it needs comes from that. :)

Curies discovered Radium and Polonium.She took 4 years to get sample of radium.Marie think the radium sample glowed because Atoms in certain elements can break apart and release energy.

The mineral has a pitch-black hue. German miners gave it the name "blende" because they thought it had several different metals mixed together. Radium, lead, helium, and a number of actinide elements are only a few of the radioactive substances found in pitchblende that can be linked to the decay of uranium.

As part of their investigation into pitchblende in 1898, the Curies discovered the elements polonium and radium.

In honor of Pierre, who sadly perished in a Paris street accident in 1906 at the age of only 46, the radioactivity unit was finally given the name "curie." The Curie family amassed an astounding number of Nobel Prizes as a result of Marie's continued labor. Together with Henri Becquerel, Pierre and Marie shared the physics award in 1903. In 1911, Marie won the chemistry Nobel Prize all by herself. Their daughter Irène married the French physicist Frederic Joliot, and she and her husband shared the 1935 Nobel Prize in Chemistry for discovering how to intentionally create radioactivity in a lab. Marie Curie passed away from radiation-induced leukemia at the age of 66 the previous year.

Marie think the radium sample glowed because Atoms in certain elements can break apart and release energy.

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Answer:

absorption of light and Carbon Fixation

Explanation:

The way that continental crust different from oceanic crust is that option B: Oceanic crust is thinner and younger.

Oceanic crust is much, much younger than continental crust, mostly as a result of subduction. The Ionian Sea, which is a component of the eastern Mediterranean basin, contains or has the oldest known oceanic crust.

Therefore, Oceanic crust differs from continental crust in a number of respects, including thickness, as well as density, age, and also that of chemical make-up. However, in subduction zones, oceanic crust is likewise destroyed.

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Given the fact that we are seeing a rise in the temperature of the globe, the artic animals in that ecosystem must adapt by a reduction in the rate of metabolism.

Several evidences continue to emerge that the temperature of the earth have continued to increase and this is largely due to the fact that since the turn of the twentieth century and the rise of industrialization, there have been a rise in the emission of the carbon dioxide and other green house gases into the environment. As a result of this, the temperature of the earth has continued to rise steadily leading to the melting of the ice cover and the destruction of ecosystems that are found around the artic regions of the earth.

Now, we know that an organism is able to adapt to the changes that occur in its habitat by being able to alter some of its structure and function.

Given that the organisms that live in the artic are adapted to cold regions and low temperatures, the metabolic rate of the organisms is high in order to produce heat.

As a result of the rise in global temperatures, the organisms would have to reduce their rate of metabolism.

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Her experiment doesn't observe the law of conservation of mass

The law of conservation of mass states that in a chemical reaction mass is neither created nor destroyed and law of conservation of mass does not says that when any compound burned the ribbon in oxygen and collected all the pieces of white ash then its mass doesn't change its always constant so in the given data

A student determined the mass of a piece of magnesium ribbon and it was 3.0 g she then burned the ribbon in oxygen and collected all the pieces of white ash (magnesium oxide) and then mass of the ash is 0.5g so here when burn the compound the mass changes so this reaction does not followed the law of conservation of mass

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The largest ionic radius is strontium.

Barium +2 has the largest ionic radius because the atomic number of barium is 56. This means that the form of barium is larger than Ca +2, Mg +2. All these ions are isoelectronic as they contain 18 electrons each. For isoelectronic ions, the positive nuclear charge is small and the ion size is large. The electron cloud expands, increasing the size of negative ions. Therefore, the correct order of increasing ionic radius is Mg2+

The ionic radius increases within the group. In the next option, strontium has the largest ionic radius because the elements placed in the periodic table are beryllium magnesium calcium and strontium. These elements belong to the alkaline earth metals. Both structural analysis and solvation energy calculations together indicate that Li+ adopts a rigid solvation structure.

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The answer is the first one.

As a result of the reaction between oxygen and methanethiol (CH_3SH), 25.8 grams of sulfur dioxide (SO_2) are produced, and the limiting reactant is oxygen (O2).

This is further explained below.

A process that results in the change of one set of chemical substances into another set of chemical substances is referred to as a chemical reaction.

Generally, the equation for the chemical reaction is mathematically given as

[tex]\mathrm{CH}_3 \mathrm{SH}(g)+3 \mathrm{O}_2(g)+2 \mathrm{H}_2 \mathrm{O}(g)+\mathrm{CO}_2(g)+\mathrm{SO}_2(g)[/tex]

[tex]Number \ of \ moles = \frac{ Given \ mass}{Molecular \ mass}[/tex]

moles of methanethiol=[tex]\frac{27.3}{48.11}[/tex]

moles of methanethiol=0.56moles

moles of oxygen [tex]= \frac{32.01}{38.6}[/tex]

moles of oxygen [tex]= 0.82 moles[/tex]

Considering the response,

When one mole of CH_3SH interacts with three moles of O_2, one mole of SO_2 is produced.

As a result, 0.56 moles of CH_3SH undergo a reaction, which results in 0.56 moles of SO_2 being produced.

0.56 grams of SO_2 are created, which is equal to 35.86 grams.

moles of SO₂ [tex]= \frac{35.86}{ 64.06}[/tex]

moles of SO₂  = 0.55 moles

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An existing ecosystem can suffer from damage from invasive species in many different ways, such as shifting habitats and depriving native creatures of food and resources.

An invasive species is an organism that damages the environment or the economy in a new location in which it is not native. Invasive species may disrupt the food chain of a ecosystem by killing or substituting natural food sources. The invasive species could provide little to no food value to wildlife.

Accidental introduction of invasive species into a new area is common. In Central Asia, the Black Sea and the Caspian Sea are home to zebra mussels. Zebra mussels accidently made their way to the Great Lakes of North America after becoming affixed to massive ships that sailed between the two areas.

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The student added sodium chloride in order to precipitate lead II chloride because this is a positive test for lead II ions.

Some times when we carry out an aqueous phase reaction, the products of the reaction would be found to be in the solid phase. This implies that one of the products of the reaction is insoluble in water and separates out of the solution.

In this case, the student knows that lead II chloride is insoluble in water thus it is obtained upon the addition of sodium chloride. This informed the addition of the sodium chloride solution.

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Missing parts;

A 50.0 mL unknown aqueous sample was tested in the laboratory. The unknown sample was identified

to be lead (II) ions by a precipitation reaction with sodium iodide. Since the unknown was identified to

have lead (II) ions in it, a student added excess sodium chloride (NaCl) to the 50.0 mL sample. A white

precipitate was made and was subsequently filtered, washed, and dried to completion. The precipitate

was measure to have a mass of 2.350 grams.

(a) How did the students determine through the addition of sodium iodide that the sample had lead (II)

ions in it?

Answer:

Explanation:

Copper Sulfate

Answer:

The electron structures of the group 14 (4A) elements are similar in that they are all part of the carbon group. Thus, they each have 4 electrons in their valence shell. Also, most of these elements are found in our daily lives except germanium. They are different in that their properties differ greatly despite them being somewhat alike.

Explanation:

I hope this helps! I took this class last year.