Please help me I am so confused. :)

The statement scientists have discovered new planets orbiting a star by detecting a wobble in the star's motion shows how scientists use observations to gain a new understanding of the world (Option A).

A planet's orbit is a route that a planet as a celestial body has around its star in a star system. The orbit of a planet can be detected by observing the light emitted by the star, which is fundamental for astronomers.

Therefore, we can conclude that scientists discovered new planets through the identification of features associated with star's movement in space (Option A).

Complete question:

Scientists are always learning new things. Which of the following shows howscientists use observations to gain new understanding about the world?

A. Scientists have discovered new planets orbiting a star by

detecting a wobble in the star's motion.

B. Scientists hope to learn more about how many stars are in space.

C. Scientists wonder if other planets can support life, and some

scientists wonder if there are aliens.

D. Scientists are familiar with some galaxies, but they do not know

how many galaxies exist.

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146 mL of 0.0755 m phosphoric acid can be neutralized with 130 ml of 0.245 m sodium hydroxide.

First of all, let's write a balanced equation.

The balanced equation is given below.

H₃PO₄ + 3 NaOH ⇒ Na₃PO₄ + 3 H₂O

Now calculate the moles of sodium hydroxide taking part in the reaction.

130 ml of 0.245 m sodium hydroxide react.

0.13 L x  0.245/L = 0.03185 moles

Now let's calculate the reacting moles of H₃PO₄.

The molar ratio of H₃PO₄ to NaOH is 1:3.

The reacting moles of H₃PO₄ are 1/3 x 0.03185 moles = 0.011 moles

Let's calculate the reacting volume of phosphoric acid

We have 0.011 moles of H₃PO₄ are in a 0.0755 M solution.

0.011 mol x 1L/0.0755 x 1,000 mL1/L = 145.6 mL (approx 146 mL)

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Nitrogen exists as a diatomic molecule, N2 (subscript 2). It exists as a gas at room temperature because of the type of interactions with other identical molecules: weak intermolecular forces are present between the molecules, specifically temporary dipole-dipole interactions.

These interactions are the second weakest type of intermolecular force (Van Der Waals and Hydrogen Bonds are the other two with Hydrogen Bonds being stronger).

Now the reason why Nitrogen exists as a gas is because these weak intermolecular forces can be overcome with little energy. Therefore, at room temperature, Nitrogen exists as a gas.

Now if we wanted to get liquid Nitrogen (quite common in Science demonstrations) we would have to cool Nitrogen down to -195.8°C (77.35°K). The energy of the particles would decrease so much that the dipole-dipole interactions would be strong enough to hold the molecules of Nitrogen together in a liquid state.

Intermolecular forces such as dipole-dipole forces, London dispersion forces exist between molecules and these depend on strength of electronegativity of molecule. Intermolecular forces of attraction decides the states of a matter.

Intermolecular forces of attraction is force of attraction that make two molecule come closer. Intermolecular forces of attraction is directly proportional to the electronegativity of the molecule.

Intermolecular forces of attraction play an important role in deciding the states of a matter. Nitrogen is a gas because its molecule have vanderwaal force of attraction. Water is a liquid because its molecule have hydrogen bonding.

Therefore, intermolecular forces of attraction decides the states of a matter.

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The volume of the object is calculated out to be 6.5 mL when the volume of your element completed displacement which is calculated.

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A polar organic solvent that is capable of forming intermolecular hydrogen bonds is called a polar protic solvent. This type of solvent forms ion-dipole interactions with anions.

What is a polar organic solvent?

Polar solvents are solvents that have both  “positive” and “negative” charge at different places in their structures and will dissolve other polar substances. An example of polar solvent is Water; other polar solvents include acetone, acetonitrile, dimethylformamide (DMF), dimelthylsulfoxide (DMSO), isopropanol, and methanol.

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It is necessary to dilute the given substances prior to determining the pH because the concentrated solutions prevent contact with the pH meter and give lower values.

A solution's acidity may be determined by looking at its pH, which is a measurement of hydrogen ion concentration. Pure water slightly separates into ions with roughly equal amounts of hydrogen and hydroxyl (OH) ions.

Detergents, soaps, and shampoos all include surfactants, and when they are concentrated, their activity prevents the surfactant from making adequate contact with the pH meter's electrode, resulting in readings that are a little lower than they should be. The pH is determined correctly when the surfactant activity is diluted in the solution.

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Molecule (a or b) in each pair has the higher boiling point also indicate force, hydrogen bonding (h), dipolar (p), or dispersion (d) is responsible for the difference so in NH₃ and PH₃ the a molecule is high melting point and forces are dispersion force and in C₂H₅OH and CH₃OHCH₃ the molecule a has high melting point and has a dispersion force and C₄H₈ and C₁₀H₂₀ the b molecule has high melting point and has a dispersion force and in HCl and F₂ the a molecule has high boiling point and has a dipolar dipole interaction forces

The forces are electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds and there are four type of forces

So here given molecule in that we have to seen the forces and high melting point so

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5. Increasing the temperature to increase molecule collisions.

An increase in the temperature of the solution can increase the solubility of a solid solute. For example, a greater amount of sugar will dissolve in warm water as compared to in cold water. The size of solute particles, stirring of the solution and increasing temperature of the solution are the three factors that can affect the solubility of a solid in a solvent. Increasing the surface area of the solute will also increase the rate of dissolving in a solution as well as increase the temperature of the solvent. Stirring will increase the speed which also increases the rate of dissolving a solid solute in a solution which helps in attaining higher solubility.

So we can conclude that temperature is the factor that increases the solubility of a solid into a solution.

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Answer:

Increase temp

Shaking/ stirring

Grinding

Explanation:

Chatgpt hehehehe

The volume does it occupy at standard temperature and pressure:

= 640mL

In order to establish experimental measurements under uniform conditions and enable comparisons between several sets of data, standard pressure and temperature requirements must be met.

Standard temperature and pressure, or STP, is a set of parameters that scientists and engineers frequently utilize. Standard pressure is 1 atm, and standard temperature is 0° Celsius (32° Fahrenheit or 273.15 K). The characteristics of various gases, for example, are described using these values.

P1V1/T1 = P2V2/T2

You simply leave that variable out from the calculation if one of these values also isn't specified because it is assumed to be a constant.

When working with moles or grams, PV=nRT is employed. If you are given grams, you must convert them to moles before you start because n is the number of moles.

STP (standard temperature and pressure) P= 1atm

T= 273K

R= 0.08206 L-atm / mol-K

P1V1/T1 = P2V2/T2

760*V1/273 = 621*798/278

V1*760*278 = 273*621*798

V1 = 640mL

The volume does it occupy at standard temperature and pressure:

= 640mL

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The covalent compounds formed from the given elements are as follows:

The collision theory states that products are formed from reactants molecules only when effective collisions occur.

Effective collisions are those collisions in which the reactant molecules that collide have energy equal to or greater than the activation energy so that product molecules are formed from such collisions.

Considering the covalent molecules that are formed from the effective collision of the given elements:

The given elements that must collide to form products include:

The given elements are all non-metals and the will most likely products that will be formed are covenant compounds.

Covalent compounds are compounds that are formed as a reseult of the formation of covalent bonds between elements. Covalent bonds are formed by electron sharing between those whose electronegativity differences are not large.

Therefore, compounds formed between the elements are covalent compounds.

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Answer:

a. Atom B will be least likely to react with other atoms as it is contains 10 electrons in neutral state with E.C. : 2,8. Since it has an octet, it is stable and does not react with other atoms.

b. Atom C forms a positive ion. It contains 11 electrons in neutral state with E.C. : 2,8,1. To attain an octet, it will donate an electron to form a positive ion.

A. 0.225

B. 4.6 kg/m3.

C. These six faces are made of three pairs of congruent faces.

For an object to be a right-angled prism all six faces must be rectangular opposite faces must be equal, and cross-sections along the length must be equal. You can draw a rectangle on the paper, but you can also make a rectangular prism out of real materials such as wood. A right-angle prism is a three-dimensional object with rectangular faces. A right-angled prism is a cube if all the faces of the prism are squares.

Prisms are named for the shape of their faces. A right-angle prism is therefore a simple prism that has rectangles as faces. A closed three-dimensional shape, but based on two rectangles. A prism is a three-dimensional shape bounded by flat faces on all sides. Prisms have two types of faces. The top and bottom are the same and are called the base. Prisms are named after the shape of these bases. For example, if the base of a prism is triangular it is called a triangular prism.

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potassium and chlorine combination of elements will form an ionic bond.

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Mass of S₈ is 130 grams

Mass is a measure of the amount of matter that an object contains

Here given data is 94.0 g of each reactant and we have to find mass of S₈= ?

Here the reaction are given

8SO₂+16H₂S → 3S₈+16H₂O

So, 3 moles S₈ will be produced from 8 moles SO₂ and 16 moles H₂S and now determine how many moles of SO₂ and H₂S are actually present during this reaction and that will allow us to then calculate the maximum mass of S₈ that can be produced

For SO₂ = 94.0 grams/(64.1 g/mole) =1.44 moles SO₂

For H₂S = 94.0g H₂S (34.1 g/mole) = 2.70 moles H₂S

2.70 moles H₂S(3 moles S₈/18 moles H₂S) = 0.506 moles of S₈

The molar mass of S₈ is 257 g/mole.  

Therefore, 0.506 moles S₈×(257 g/mole S₈) = 130 grams S₈

So  S₈ = 130 grams

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To prepare ammonium fertilizer we will react ammonia gas with nitric acid to form a solution and heat also get released during this.

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Answer:

25 K

Explanation:

298-273=25 Kelvin

Sample 2 has correctly identifies how mass, mole, and atoms are related because half of the atomic mass would equal half of a mole and half of 6.02 x 10²³ atoms.

Atomic mass of Helium (He) is 4g. In the data, it is provided that the mass of He is 2g. It means helium with half of the atomic mass.

No. of moles = Atomic mass / Molar mass

No. of moles of He = 2 / 4 = 0.5

Thus, Helium with half of atomic mass would be equal to mass of half mole i.e., 0.5 mole.

A mole of a compound contains 6.02 x 10²³ atoms. So, half mole of helium would have half atoms i.e., 3.01 x 10²³ atoms.

On consolidating, Sample 2 correctly identifies the relationship between mass, mole, and atoms because half of the atomic mass would equal half of a mole and half of 6.02 x 1023 atoms.

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By looking on the map and the fossil of bird found on different places shows that in past these land masses were connected.

Fossils are defined as the geologically altered remainders of the living organism which are exist in the world once or its behaviour.

There are basically five main types of fossil

In 1983, a team of scientists discovered a fossilized bone of a giant bird when excavating land in Brazil. After studying the fossil, the team thought that the bird was unique to South America but had been extinct for millions of years. Many years later, another fossil from the same giant bird was found in Nigeria. The two fossils were formed in rock that was very similar to one another. This shows that the two land masses are connected.

Thus, we concluded that the fossil of bird found on different places shows that in past these land masses were connected.

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

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

E = hf

Where;

According to this question, the frequency of a wave is given as: 4.25 x 10⁸ Hz. The energy can be calculated as follows:

E = 6.626 × 10-³⁴ × 4.25 x 10⁸ Hz

E = 2.816 × 10-²⁵J

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

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1. The amount, in grams, of the new substance that Clarice should expect is 15 grams.

2. The law that supports the answer is the law of conservation of mass.

3. The law opines that mass is conserved in every chemical reaction.

The law of conservation of mass states that masses are conserved in chemical reactions. They can, however, change forms during the course of reactions.

In other words, if 10 grams of sugar reacts with 5 grams of another substance, the total amount of the final product should be the addition of the two masses. Unless parts of the reactants or products have been converted to something else that is not captured.

So, in the case of Clarice, the mass of the new substance that should be expected would be:

10 + 5 = 15 grams.

Since gases were not involved in the reaction and there is no mass loss in any other form. The mass of the final product should be 15 grams.

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The molecular weight of the unknown gas is  42.06 g.

The idea is that the density of the gas tells you the mass of this gas that occupies exactly 1 L under some unspecified pressure and temperature conditions.

In this case, you know that the density of the gas was 1.51g/L.

This means that 1.51 g/L of this gas occupies exactly 1 L under the pressure and temperature conditions used in the experiment.

You are also aware that the total volume of the flask is 2.00 L. At this point, you can use the density of the gas to calculate the mass of gas required to fill the given volume with the sample.

[tex]2.00 L . \frac{1.51g}{1L} =3.02g[/tex]

You must now determine the mass of exactly one mole in order to determine the molar mass of the gas. Since you are aware that this sample contains 0.0718 moles of gas and weighs 12.5 g, you can infer that one mole will weigh that much.

[tex]1 mol. gas .\frac{3.02g}{0.0718} =42.06g[/tex]

As a result, the gas's molar mass can be expressed as molar mass = 42.06 g/ mol.

This indicates that 42.06 g makes up 1 mole of this gas.

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The Sun does not "burn" as we think of logs in a fire or paper burning. The Sun glows because it is a very big ball of gas, and a process called nuclear fusion is taking place in its core.

Nuclear fusion occurs when one proton smashes into another proton so hard that they stick together and release some energy as well. This energy then heats the other materials (other protons and electrons and such) nearby.

This heating eventually grows out from the center (or core) of the star to the outside, finally leaving the surface and radiating out into space to be the heat and light we know stars emit.

People, including scientists, sometimes say that the Sun "burns hydrogen" to make it glow. But that is just a figure of speech. Hydrogen doesn't burn, it fuses, into helium. So no oxygen is required!

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Answer: The minimum amount of energy which the reacting species must possess in order to undergo a specified reaction.

Explanation:

Answer:

3.29 grams NaCl

Explanation:

I assume 0.45m is 0.45 molar.  The m is usually capitalized, to prevent confusion with meters, moles, etc. : 0.45M

It is very useful to use of the definition of molar in the thought process.

The definition of molar, M, is moles solute per liter of solution.  The term 0.45M NaCl means that a solution has 0.45 moles of NaCl in 1 liter of solution.  a half-liter would have 0.225 moles of NaCl, which is equivalent to 0.45 moles/liter. in terms of concentration.

We'll need the molar mass of NaCl, which is:

Na:  23.0

Cl:   35.5

       58.5 grams/mole

========

Now let's calculate how many moles of NaCl are needed.  We want 125ml (0.125L) of 0.45M NaCl.

(0.45 moles NaCl/Liter)

multiply that by the actual volume required:

(0.45 moles NaCl/Liter)*(0.125Liter) = 0.0563 moles NaCl

[The liters unit cancels, leaving only moles NaCl.  The units are helpful in understanding the mathematical steps required and help insure a correct answer.]

To get grams NaCl, multiply by the molar mass of NaCl:

(0.0563 moles NaCl)*(58.5 grams NaCl/mole NaCl) = 3.29 grams NaCl

Note the units:  moles NaCl cancel, leaving grams NaCl.

=====

There is a useful relationship to remember concerning the dilution of a solution.  It is not needed here, but it does highlight the usefulness of understanding units.  When diluting a volume, V1, of a solution of concentration M1 to achieve a concentration and volume of of M2 and V2, we can use:

  M1V1 = M2V2

Example:   125 ml of 1M HCl is needed for an experiment.  The only supply is 5M HCl.  How much of the 5M HCl is needed to make 125ml of the 1M HCl?

M1 = 5M HCl

V1 = The unknown

M2 = 2.5M HCl

V2 = 100 ml

M1V1 = M2V2

(5M)*(V1) = (1M)*(125ml)

V1 = (1M)*(125ml)/(5M)

V1 = 25 ml

25 ml of 5M HCl may be added to 75 ml of water (slowly) to form 100ml of 2.5M HCl.

===========

Extra material:  This is not relevant to the original problem, but it demonstrates the importance of units and the fact that it is the moles of a substance that is the important element.  

If the concentration and volume of M1V1 are in moles/liter and liter, the term M1V1 has units of:

(moles/Liter)*(L), which reduces to moles of the substance.

The same with the term on the right, M2V2:  it also reduces to moles.  So the equation is simply saying that whatever number of moles one starts with, the same number of moles will wind up in the final solution.

A bonus discovery is that the volume units cancel in this calculation.  It seems unlikely, but this means the volumes don't need to be adjusted from ml to liters, since volume unit cancels out.

If the original problems stated that the goal is to make 125 ml of 0.45M NaCl from a stock of 1.0M NaCl solution, the calculation would be:

M1 = 1.0M NaCl

V1  = ?

M2 = 0.45M NaCl

V2 = 125 ml

M1V1 = M2V2

(1.0M)*(V1) = (0.45M)*(125ml)

V1 = 56.25 ml

68.75 ml of water may be added to 56.25 ml of NaCl to form 125 ml of 0.45M NaCl.

Although M is expressed as moles/liter, we don't need to convert the volumes to liters, because the M unit cancels out.  That doesn't feel correct, but it is - the unit cancellation is legal.

Answer: Yes, most bacterial cells have double stranded dna

Explanation:

Answer:

yes

Explanation:

prokaryotic cells are unique bacteria that has DNA. it has a single cell called nucleoid in a cytoplasm that organise DNA differently

Norman sliding his foot across the floor would create heat energy through friction (C)

When a person is sliding on the floor, the foot would rub against the floor. The process would result in friction between the feet and the floor.

In addition to that, the potential energy (resting energy) is getting converted to kinetic energy (energy resulting from motion). The difference between the energy of an object at resting state and motion would result in production of heat energy. This is caused mainly due to friction.

Thus, when Norman’s foot is sliding across the floor, it would create heat energy through friction.

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Explanation:

The effects of inhaled nanoparticles in the body may include lung inflammation and heart problems. Studies in humans show that breathing in diesel soot causes a general inflammatory response and alters the system that regulates the involuntary functions in the cardiovascular system, such as control of heart rate.

625 km

1 km = 1000 meters

625 x 1000 = 625000 meters

1 meter = 100 centimeters

625000 x 100 = 62500000 centimeters

1 cm = 10 mm

62500000 x 10 = 625000000 millimeters