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Answer:

In Niels Bohr's theory of the atom, electrons absorb and emit radiation of fixed wavelengths when jumping between fixed orbits around a nucleus. The theory provided a good description of the spectrum created by the hydrogen atom, but needed to be developed to suit more complicated atoms and molecules.

Explanation:

Answer:

69

Explanation:

Answer:

2. reasoning

Explanation:

PLS GIVE BRAINLIEST

Given the balanced equation:

( Reaction type : double replacement)

CaF2 + H2SO4 → CaSO4 + 2HFI

We can determine the number of grams prepared from the quantity of 75.0 H2SO4, and 63.0g of CaF2 by converting these grams to moles per substance.

This can be done by evaluating the atomic mass of each element of the substance, and totaling it to find the molecular mass.

For H2SO4 or hydrogen sulfate it's molecular mass is the sum of the quantity of atomic mass per element. H×2 + S×1 + O×4 = ≈1.01×2 + ≈32.06×1 + ≈16×4 = 2.02 + 32.06 + 64 = 98.08 u (Dalton's or Da) or g / mol.

For CaF2 or calcium fluoride, it's molecular mass adds 1 atomic mass of calcium and 2 atomic masses of fluoride due to the number of atoms.

Ca×1 + F×2 = ≈40.07×1 + ≈19×2 = 40.08 + 38 = 78.07 u (Da or Dalton's) or g / mol.

The limiting  reactant in the given balanced reaction is sulphuric acid. The mass of HF produced from 75 g of H₂SO₄ is 30 g.

The limiting reactant in a species is the reactant which is fewer in amount and thus determine the yield of the product.

In the given reaction, one mole of calcium fluoride reacts with one mole of sulphuric acid to give two moles of HF. The molar mass of calcium fluoride CaF₂ is 78 g/mol the weight taken here is 63 g. Thus number of moles is 63/78 = 0.87 moles.

The molar mass of sulphuric acid H₂SO₄ is 100g/mol. The weight taken here is 75 g and thus, number of moles is 75/100 = 0.75 moles. One mole of calcium fluoride need one mole of H₂SO₄ . Thus 0.87 neede 0.87 moles of H₂SO₄ . But here we have only 0.75. Thus it is the limiting reactant.

As per the reaction, one mole or 100 g of H₂SO₄  produce 2 moles or 40 g of HF (molar mass = 20 g/mol). Thus mass of HF produced from 75 g is calculated as follows:

mass of HF = (75 × 40)/100

                   =  30 g.

Hence, mass of HF produced in this reaction is 30 g.

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Answer:

I think it is D.

Explanation:

Answer:

b

Explanation:

Answer:

An atom that has a negative or positive charge it is called an ion.

Answer:

It''s called a Cation

Explanation:

The bouncing back of light waves observed when light waves hit ice and most of them bounce off and radiate back into space is called reflection.

Light waves are a form of waves which produces visible sensitization of the eyes

Light waves have properties of waves such as:

When light waves hit ice, most of them bounce off and radiate back into space.

This property of light waves is known as reflection.

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When light waves hit ice, most of them bounce off and radiate back into space, hence, ice is best described as a reflective surface.

A reflective surface is one which can cause incident light to bounce back (reflection).

According to this question, when light waves hit ice, most of them bounce off and radiate back into space. This means that most of the incident light reflects off the ice surface.

Therefore, the ice surface is best described as a reflective surface.

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Answer:

2.Diffusion

Explanation:

As we metabolize certain nutrients for the correct functioning of our cells, carbon dioxide is produced as a result. We need oxygen in order to metabolize them, so we need to have a system to incorporate it, and to eliminate the carbon dioxide produced.

This system is provided by the interaction between the respiratory system, which allows the enter of oxygen into the body and gets rid of the carbon dioxide, and the circulatory system, which acts transporting carbon dioxide and oxygen to and from the lungs, respectively.

The surface available for the gaseous exchange is enlarged by the pulmonary alveoli. The alveoli are the terminal aerial spaces of the respiratory system and the structures where the exchange between the air and blood is produced. Each alveolus is surrounded by a net of capillaries, where oxygen is freed from the hemoglobin and moves into the cells by diffusion. Carbon dioxide, diffuses out of the cells into the capillaries, where most of it dissolves in the plasma of the blood.

here is what came up when i searched it up:

"The attraction between protons and electrons can also make clothes stick together in the dryer. When you dry clothes in the dryer, different fabrics rub together, and electrons from a cotton sock (for instance) may rub off onto a polyester shirt."

Sometimes, clothes can get stuck together after they come out of a dryer because of static electricity.

No, clothes may not start off as neutral. Whether clothes have static charges before going into the dryer depends on different things.

Static electricity happens when certain things touch and create an uneven amount of electrons. This can cause one material to have a positive charge and the other to have a negative charge. When clothes move and touch each other in a dryer, this rubbing can cause static electricity.

If the clothes are cleaned and dried correctly, they should have no charge or be evenly charged.

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Answer:

Here

Explanation:

Some assume our planet's changing distance from the sun causes the change in the seasons. That's logical, but not the case for Earth. Instead, Earth has seasons because our planet's axis of rotation is tilted at an angle of 23.5 degrees relative to our orbital plane, that is, the plane of Earth's orbit around the sun

The initial temperature of the metal = 35 °C

Heat can be formulated :

Q = m . c . ΔT

Q = heat, J

c = specific heat, J/g C

ΔT = temperature, °C

m = 20 g

c = 5 J/(g°C)

Q = 500 J

T₁ = 40 C

the initial temperature :

[tex]\tt \Delta t(T_2-T_1)=\dfrac{Q}{m.c}\\\\40-T_1=\dfrac{500}{20.5}\\\\40-T_1=5\\\\T_1=35^oC[/tex]

Answer:

Check explanation section.

Explanation:

In order to understand balanced force and unbalanced forces the first law of Newton should be considered as a basic knowledge.

For Balanced forces, there is equal equality in the direction of the forces. In balanced forces, there is no acceleration.

For unbalanced forces, there is acceleration that is go say there is going to be movement. Therefore, net force is equal to unbalanced forces.

(i) Suitcase dropped from a height.

Answer: since there is movement that is acceleration, then the force here is unbalanced force. The resultant force is downwards.towards the greater force direction.

(ii) A bicycle moving with constant velocity on a straight road.

Answer: As the bicycle moves at constant velocity on the straight road the force here is Balanced. Frictional forces balances the forces from the cyclist.

(iii) The rope does not move in a tug of war on applying force at both ends.

Answer: Balanced force.

Mass of KMnO4 required : 31.607 g

The reaction equation is the chemical formula of reagents and product substances  

A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products  

Reaction

2KMnO₄ → K₂MnO₄ + MnO₂ + O₂

mol of O₂ :

[tex]\tt \dfrac{1.6}{16}=0.1[/tex]

mol ratio KMnO₄ : O₂ = 2 : 1

mol of KMnO₄ :

[tex]\tt \dfrac{2}{1}\times 0.1=0.2[/tex]

mass of KMnO₄ :

MW KMnO₄ : 158,034 g/mol

[tex]\tt mass=0.2\times 158,034 =31.607~g[/tex]

Answer:

force

Explanation:

because the force

Hello there!

Your answer is C.

Answer:

The right option is; A. It is younger than the rock layer below.

Explanation:

A rock layer deposited on top of another rock layer is younger than the rock layer below. This is based on the law of superposition which states that in any undeformed sequence of rocks that are laid down in layers, the youngest layer of rock will be on top of the sequence, while the oldest layer will be at the bottom of the sequence.

Answer & Explanation:

Susana's red crystal sample is a compound because it was broken down into a gas and blue powder. It is not an element because elements cannot be broken down into simpler substances by ordinary means, such as heating.

Answer:

Susana's red crystal sample is a compound because it was broken down into a gas and blue powder. It is not an element because elements cannot be broken down into simpler substances by ordinary means, such as heating.

Explanation

Sample response form Edg

The question is asking you to compare each elements electrons, specifically valence since it mentioned their placement on the table.

Similarly: they both are only one electron away from stability (a full octet)

Difference: Sodium will want to loose the one electron, and Chlorine will take it.

Josh is washing glasses with soap and water. He is afraid to carry the glasses because they are slippery. Josh could dry them with a towel to keep the glasses from being slippery.

Glasses are visual eyewear that have lenses fixed in a frame that holds them in front of a person's eyes. The frame often has a bridge over the nose and arms that rest over the ears. Glasses are also known as eyeglasses or spectacles.

The term "glasses" likely originated from the word "spyglass," which was originally used to describe "a pair of eyeglasses" that had to be held up to the eyes in order to be fully effective.

Eyeglasses, often known as glasses or spectacles, are lenses that are mounted in frames and worn in front of the eyes to improve vision or to correct astigmatism, myopia, or hyperopia.

Thus,  Josh could dry them with a towel to keep the glasses from being slippery.

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Answer:

ductile - germanium

mellabe - zirconium

Answer:

-320f

Explanation:

Answer:

false

Explanation:

Weathering describes the breaking down or dissolving of rocks and minerals on the surface of the Earth. Water, ice, acids, salts, plants, animals, and changes in temperature are all agents of weathering.

Answer:

0.007 mol

Explanation:

Step 1: Given data

Volume of acetaminophen: 0.8 mL

Step 2: Calculate the mass corresponding to 0.8 mL of acetaminophen

The density of acetaminophen is 1.26 g/mL.

0.8 mL × (1.26 g/mL) = 1 g

Step 3: Calculate the number of moles corresponding to 1 g of acetaminophen

The molar mass of acetaminophen is 151.16 g/mol.

1 g × (1 mol/151.16 g) = 0.007 mol

Answer:

the line represents the condition where pressure and heat have the same effects.

Answer: C) The melting point of a substance at a specific pressure.