A scientist has been collecting data on the soil composition in a forest after a wildfire. Every year she visits the forest and takes a sample from the same area. She then analyzes the sample and determines its content. She plans on collecting data for ten years and then determining the trends that have occurred. Which type of investigation is the scientist performing?


collective

comparative

experimental

descriptive

Aluminum sulfide is Al₂S₃, which shows that there are 3 sulfur atoms per formula unit.

In one mole there is Avogadro’s number of atoms and Avogadro’s number = 6.02 x 10²³

In 1.10 mole = 1.10 x 6.02x10²³ = 6.62 x 10²³ formula units

Now multiply with 3 to get number of sulfur atoms present in 1.10 mol of Aluminum sulfide;

3 x 6.62x10²³ = 1.99 x 10²⁴

So, the answer is 1.99 x 10²⁴ sulfur atoms.

Hertz extended Maxwell’s idea that light is produced by the interaction of electric and magnetic fields.

Answer:

Hertz extended Maxwell’s idea that light is produced by the interaction of electric and magnetic fields.

Explanation:

According to Maxwell electromagnetic waves propagated perpendicular to the direction of the oscillating mutually perpendicular electric and magnetic field. This electromagnetic disturbance could move through vacuum with the speed of light and had wave like properties.

Hertz designed experiments which proved Maxwell's idea: the electromagnetic nature of light.

All isotopes of an element have the same number of protons and different numbers of neutrons. So, the isotopes Oxygen-16, Oxygen-17, and Oxygen-18 have different numbers of neutrons, not protons or electrons.

The three isotopes, Oxygen-16, Oxygen-17, and Oxygen-18, are all isotopes of the element Oxygen. This means that they have the same number of protons, as the number of protons determines the identity of an element. In this case, Oxygen isotopes all have 8 protons. However, isotopes of the same element can have different numbers of neutrons. Indeed, Oxygen-16, Oxygen-17, and Oxygen-18 have 8, 9, and 10 neutrons respectively. They also have an identical number of electrons as protons to make the atom electrically neutral.

So, the statement 'They have different number of neutrons' is the correct one among the options.

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Its dune. The Delta landform is involving water, not sand. Dunes are basically sand, so i would pick dune

Answer:

The theoretical yield is calculated from the amount of the limiting reactant present.

Explanation:

The limiting reactant is one which is present in lesser amount than the other reactant (based on molar ratio requirement)

For example in formation of water we need one mole of hydrogen gas and half moles of oxygen gas. Now we have one mole of hydrogen gas and one mole of oxygen gas then the limiting reagent is hydrogen gas.

theoretical yield is the expected yield of a reaction calculated based on the moles or amount of limiting reagent present as the limiting reagent is going to be completely consumed during the reaction.

Answer : The correct option is, (D) The theoretical yield is calculated from the amount of the limiting reactant present.

Explanation :

Excess reagent : It is defined as the reactants not completely used up in the reaction.

Limiting reagent : It is defined as the reactants completely used up in the reaction.

Theoretical yield : It is calculated from the amount of the limiting reagent present in the reaction.

Actual yield : It is experimentally determined.

Hence, the correct option is, (D) The theoretical yield is calculated from the amount of the limiting reactant present.

Answer:

1. less reactive than sodium

Explanation:

The wavelength (in nanometers) of a photon emitted by a hydrogen atom when its electron drops from the n = 5 to n = 3 state is 1280nm.

The term wavelength defined as the distance between the two successive crests or troughs of the wave. Wavelength is denoted by the greek word lambda (λ).

The distance between the "crest"  of one wave to the crest of the another wave is the wavelength. We can measure from the "trough" of one wave to the trough of the another wave we get the same value for the wavelength.

The difference in energy (E) between two shells calculated as follows:

ΔE = -RH [(1 / nf2) - (1/ni2)] ΔE

= -2.18 x10-18 J [(1/32) - (1/52)] ΔE

= -1.55 x10-19 JE

hc/λλ = hc/Eλ

= [(6.63 x10-34 J.s.) x (3.00 x1017 nm/s)] /(1.55 x10-19 J)

λ = 1280nm

Thus, The wavelength of a photon emitted by a hydrogen atom when its electron drops from the n = 5 to n = 3 state is 1280nm.

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The particle that an atom can lose or gain in order to form a charged ion is electron.

When an atom lose an electron from their valence shell the it form positive charged ion known as cation.

When an atom gain an electron from their valence shell then it form negative charged ion known as anion.

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Answer:

it is c

Explanation:

The solution is not a pure substance because it is a mixture between a solute and a solvent. Therefore, option (C) is correct.

Pure substances can be described as elements that cannot be broken down into simple substances that contain only one kind of atom in the whole composition.

A pure substance can be described as made up of two or more chemical elements that are chemically combined and has a set composition such type of pure substance is called a compound. For example, water is a pure compound that is composed of hydrogen and oxygen in a whole ratio of 2:1.

A mixture can be described as made up of two or more different substances which are only physically combined but not chemically. A mixture can be separated into its original components.

The composition of a heterogeneous mixture does not have uniform throughout the mixture while the composition in a homogeneous mixture is always the same.

Therefore, the solution is a mixture, not a pure substance.

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Copper, silver, mercury, and gold are less reactive than hydrogen as they are positioned at the bottom of the activity series and do not readily react with acids to produce hydrogen gas.

The metals listed that are less reactive than hydrogen (H2) are those found at the bottom of the activity series. Specifically, these metals include copper (Cu), silver (Ag), mercury (Hg), and gold (Au). These metals do not react with acids to form hydrogen gas and hence are considered less reactive than hydrogen. Additionally, in the context of the electrochemical series, these metals are known as inert metals, indicating their low reactivity and their position at the very bottom of the activity series. Therefore, they do not readily corrode in the presence of dilute acids.

It's important to note that aside from basic trends, the exact order of reactivity of metals can be determined from the activity series or electrochemical series, where the lower a metal's position relative to hydrogen, the less reactive it is in comparison.

Uv gel enhancements rely on ingredients from the monomer liquid and acrylic chemical family.

Isotopes of a particular element are alike in that they all have the same atomic number which means they have the same number of protons. However, they differ in the number of neutrons.

The isotopes of a particular element are alike in that they all have the same number of protons in the nucleus, hence, they are all part of the same atomic family and share the same atomic number. This determines the element's position in the periodic table and its chemical properties. For example, all isotopes of Hydrogen - Protium, Deuterium and Tritium - have one proton each.

However, isotopes of a same element differ in their number of neutrons. For instance, while Protium has no neutrons, Deuterium has one and Tritium has two.

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Copper has an atomic number of 29, 4 copper atoms contain 116 electrons, while 3 copper atoms can be formed from 87 protons.

The atomic number of an element tells us the number of protons in an atom of that element.

1. Since copper has an atomic number of 29, each copper atom has 29 electrons as well. To find the total number of electrons in 4 atoms of copper, we can simply multiply the number of electrons in one copper atom by 4.

So, there are 4 [tex]\times[/tex] 29 = 116 electrons in 4 atoms of copper.

2. Since each copper atom has 29 protons, we can divide the total number of protons by 29 to find the number of copper atoms that can be made.

[tex]\dfrac{87}{29} = 3[/tex]

So,87 protons can make 3 copper atoms.

Therefore, there are 116 electrons in 4 atoms of copper and 3 copper atoms can be made out of 87 protons, respectively.

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Final answer:

To determine the number of moles of nitrogen in 1.61 x 10²⁴ nitrogen particles, divide by Avogadro's number, resulting in 2.673 moles of nitrogen.

Explanation:

The student is asking about the number of moles of nitrogen contained in a given number of nitrogen particles. To find this, we use Avogadro's number, which is the number of particles in one mole of a substance. The value of Avogadro's number is 6.022 x 10²³ mol−1. Since the question indicates that there are 1.61 x 10²⁴ nitrogen particles, we divide this number by Avogadro's number to determine the moles.
Here's the calculation:
Number of moles (n) = Number of particles (N) / Avogadro's number (NA)
n = 1.61 x 10²⁴ particles / 6.022 x 10²³ mol−1
n = 2.673 moles of nitrogen

By applying Charles's law - V1/T1 = V2/T2 - and rearranging the formula as V2 = V1*(T2/T1), we find that the final volume of the argon gas when the temperature is raised to 42°C under constant pressure is 5.91 L.

This question deals with the application of Charles's law, a fundamental concept in gas laws. Charles's law states that the volume of a gas is directly proportional to its temperature in Kelvin, assuming that pressure and the amount of gas remain constant.

First, convert the temperatures provided from Celsius to Kelvin. So, T1 = 15°C + 273 = 288 K and T2 = 42°C + 273 = 315 K. For the calculation, you would apply Charles's law formula - V1/T1 = V2/T2. Here, V1 is the initial volume (5.40 L), and T1 is the initial temperature in Kelvins (288 K). T2 is the final temperature in Kelvins (315 K), and we have to find V2 which is the final volume.

By rearranging the formula we get V2 = V1*(T2/T1) = 5.40 L * (315 K / 288 K) = 5.91 L.

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The molar mass of the unknown gas is 92.0 g/mole

Explanation:

Part a in an effusion experiment, it was determined that nitrogen gas, n2, effused at a rate 1.812 times faster than an unknown gas. what is the molar mass of the unknown gas? express your answer to four significant figures and include the appropriate units.

The molar mass is the mass of a sample of that compound divided by the amount of substance in that sample in moles. Molar mass and molecular weight are often confused, but their values are very different.

Graham's law states the rate of diffusion or of effusion of a gas is inversely proportional to  its molecular weight of the square root .

Graham's Law = rate of effusion of gas 2  / rate of effusion of gas 2

Graham's Law = square root (MM1 / MM2), where MM1 and MM2 are the molar masses of the gases.  

Gas_2 = N_2, therefore

1.812 =  √ (MM_1 / MM N_2)

1.812 = √ (MM_1 / 28.0)

1.812 = √ (MM_1 / √ 28.0 )

1.812 = √ (MM_1 / 5.29 )

1.812 x 5.29 = √ MM_1 = 9.59

MM_1 = 9.59^2 = 92.0 g/mole

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Answer:

c. Einstein

Explanation:

Einstein is most credited  with the idea that a quantum of light (photon) can act as a particle. He proposed that light behave as photons or  quantum of energy and used it to explain the Photoelectric Effect for which he received the Noble prize. Prior to that light was believed to behave as a wave or electromagnetic radiation only. However, photoelectric effect showed that light has particle nature as well.

The average atomic mass of an element on the periodic table is a weighted average and not a whole number because it accounts for the different masses and abundances of each isotope, whereas the actual mass of an individual atom is approximately its mass number, a whole number.

You will never find an atom that has an actual atomic mass equal to the average atomic mass of the element because the atomic mass listed on the periodic table is a weighted average of all the naturally occurring isotopes of that element. Because each proton and each neutron has a mass of approximately one atomic mass unit (amu), and electrons contribute much less, the atomic mass of each isotope is approximately equal to its mass number, which is always a whole number. However, the average atomic mass is not a whole number because it is a calculation that includes the different masses of each isotope and their respective abundance percentages. This weighted average reflects the average mass of an atom if you could randomly pick one out of a sample containing all the isotopes of that element.

For example, carbon has two stable isotopes, 12C and 13C, with respective abundances of 98.89% and 1.11%. The average atomic mass of carbon is calculated by taking into account these abundances, leading to an average atomic mass that does not match exactly the mass of either isotope. In contrast, some elements have atomic masses in square brackets, like technetium (element 43) and promethium (element 61), which indicate the mass number of their most stable isotope because these elements do not have stable isotopes with an average atomic mass.

Final answer:

A hydrogen bond is a weak attraction between the slightly positive hydrogen end of one polar molecule and the slightly negative end of another, while a covalent bond is a strong bond involving the sharing of electrons between atoms within a molecule. Hydrogen bonds are depicted with dashed lines and covalent bonds with solid lines in molecular diagrams. The hydrogen bond is much weaker than a covalent bond, requiring significantly less energy to break.

Explanation:

The key difference between a hydrogen bond and a covalent bond is the nature of the interactions that hold atoms or molecules together. In a water molecule ([tex]H_{2}[/tex]O), the oxygen and hydrogen atoms are held together by covalent bonds, which involve the sharing of electrons between atoms and are depicted by solid lines in molecular diagrams. These bonds are quite strong because they involve the sharing of electrons to create a stable electron configuration around each atom.

In contrast, a hydrogen bond is a weak attraction between the slightly positive hydrogen end of one polar molecule and the slightly negative end of another polar molecule, such as the oxygen atom in a different water molecule. This interaction is depicted by dashed lines in molecular diagrams and does not involve electron sharing; instead, it's a result of polar covalent bonds within the molecules that create slight positive and negative charges leading to an attraction between molecules. Because hydrogen bonds are between molecules, they are much weaker than the covalent bonds within molecules, requiring only about 10% of the energy to break compared to typical covalent bonds. This behavior illustrates why we can boil water, breaking the hydrogen bonds, without breaking the water molecules themselves, which would require disrupting their covalent bonds.