How many cm are equal to 1.45m

Answer: C. Saturation point

Explanation:

Answer:

attached below is the detailed solution

answer : value of constant = 2.18 * 10^-18 J

Explanation:

Express the constant in terms of h and c and RH

attached below is the detailed solution

Constant = [tex]h_{C} R_{H}[/tex]

               = ( 6.626 * 10^-34 ) * ( 3 * 10^8 ) * ( 1.097 * 10^7 )

               = 2.18 * 10^-18 J

The Planck equation and the light speed  allow us to find the results for the transformation of the Rydberg equation are:

   [tex]E = A ( \frac{1}{n_1^2}\frac{x}{y} - \frac{1}{n_2^2} )\\A= R_H \ h \ c \\A = 2.18 \ 10^{-18} j[/tex]

The Rydberg equation is an empirical expression that explains the wavelength of the emissions.

          [tex]\frac{1}{\lambda } = R_H ( \frac{1}{n_1^2} - \frac{1}{n_2^2} )[/tex]  

Where λ is the wavelength of the emitted radiation, is the Rydberg constant, n₁ and n₂ are integers with n₁ <n₂

It is asked to write the Rydberg equation  for the energy.

Let's use the Planck relation.

           E = h f

The light speed is related to the wavelength and frequency of radiation.

           c = λ f

Where E is the energy, h the Planck constant, c the speed of light, λ the wavelength and f the frequency.

Let's  substitute.

           E = [tex]\frac{hc}{\lambda}[/tex]  

           [tex]\frac{1}{\lambda} = \frac{E}{hc}[/tex]  

Let's substitute in the Rydberg equation.

          [tex]\frac{E}{hc} = R_H ( \frac{1}{n_1^2} - \frac{1}{n_2^2}) \\E = R_H \ h \ c \ ( \frac{1}{n_1^2} - \frac{1}{n_2^2} )[/tex]

We can write is an constant of the form.

          A = [tex]R_H h c[/tex]

The value of the constant is :          

          A = 1,097 10⁷ 6,626 10⁻³⁴ 3 10⁸

          A = 2.18 10⁻¹⁸ J

In conclusion, using the Planck equation and the light speed we can find the results for the transformation of the Rydberg equation are

        [tex]E = A ( \frac{1}{n_1^2} - \frac{1}{n_2^2} )\\ A = R_H h c\\[/tex]

       A = 2.18 10⁻¹⁸ J

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Answer:

Proust's law of definite proportion

Explanation:

The law of constant proportion states that the components elements of a given chemical compound combine with each other in a fixed mass ratio when the compound is produced by any given process

Therefore, from the question, the chemical formula for Nitrogen Dioxide is NO₂, where the molar mass of nitrogen, N = 14

The molar mass of oxygen, O = 16

Given that one molecule of NO₂, contains one atom of nitrogen and two atoms of oxygen, one mole of NO₂ will contain 14 grams of nitrogen and 32 grams of oxygen, according to Proust's law of definite proportion.

Answer:

C

Explanation:

the rest arent scientific

Answer:

C. Investigations

Explanation:

Test approved

Answer:

Photic Zone

Explanation:

The photic zone is the uppermost layer of the sea that recieves sunlight allowing phytoplankton to perform photosynthesis.

Answer:

O microwaves, radio waves, infrared light

Explanation:

Answer: C.  microwaves, radio waves, infrared light

Explanation: C. Microwaves, Radio Waves, Infrared light

Answer:

It is 'A' i.e., Sodium magnesium, aluminium

Elements tend to lose and gain electrons to achieve electronic stability. Lithium, sodium, and potassium are the elements that form +1 ions. Thus, option C is correct.

Cations are said to be the ions formed by donating their outermost valence electron that in return results in a positive charge on the element. Cations are said to be formed when the electron is more in number in the valence shell.

The electronic configuration is given as:

Here, there is one electron extra in the outer shell of the atom that can be donated to other atoms that are called anions (electron acceptors). Li, Na, and K can donate one electron each and hence will acquire a +1 charge.

Therefore, option C. lithium, sodium, and potassium form a +1 charge.

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Answer: Carbon-12 and Carbon-14 both have the atomic number of 6.

Explanation: They are both isotopes of one another. This means they have different amount of neutrons, resulting in different atomic masses.

Answer:

They have the same atomic number.  Carbon has the atomic number of 6 which means that all isotopes have the same proton number. However, the number of neutrons is different, thus giving different mass numbers.

Explanation:

The information we can obtain for an element from periodic table is its atomic number and chemical symbol. Thus option A and B are correct.

Atomic number of an element is the number of protons of the element. For a neutral atom the number of electrons is equal to the number of protons.

There are 118 elements in the modern periodic table and they are classified into different group and periods. Elements of same number of valence electrons and similar physical and chemical properties are classified into one group.

There are 18 groups and 7 period in  the periodic table. Each classification is based on their atomic number. Chemical symbols are used to represent the elements and they can be easily identified by the symbols.

For example, hydrogen have the chemical symbol H and oxygen with O and carbon with C. etc. Similarly we can get mass number of elements from periodic table. Thus option A and B are correct.

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Answer:

V = 34.55 L

Explanation:

Given that,

No of moles, n = 1.4

Temperature, T = 20°C = 20 + 273 = 293 K

Pressure, P = 0.974 atm

We need to find the volume of the gas. It can be calculated using Ideal gas equation which is :

PV=nRT

R is gas constant, [tex]R=0.08206\ L-atm/mol-K[/tex]

Finding for V,

[tex]V=\dfrac{nRT}{P}\\\\V=\dfrac{1.4\times 0.08206\times 293}{0.974 }\\\\V=34.55\ L[/tex]

So, the volume of the gas is 34.55 L.

Answer:

tundra bc it has barley any food source and has vary little inhabitants

Explanation:

Answer:

a patch of lichens on bare rock

Answer:

Explanation:

The overall equation for this reaction can be represented as:[tex]4 Fe(s) + 3 O_{2(g) } \to 2Fe_2O_{3(s)} \ \ \ \ \Delta H = -1652 \ kJ[/tex]

The first question says:

How much heat is released when 4.40 moles of iron is reacted with excess O₂?

Suppose 1652 kJ of heat is being emitted into the surroundings when four(4) moles of Fe reacted with O₂, therefore;

4.40 moles of Fe reacts with:

[tex]=\dfrac{4.40 \ moles \times 1652 \ kJ}{4 \ moles}[/tex]

= 1817.2 kJ of heat will be produced.

The second question says:

How much heat is released when 1.00 mole of [tex]Fe_2O_3[/tex] is produced?

Given that 1652 kJ of heat is being emitted into the surroundings when two(2) moles of [tex]Fe_2O_3[/tex] is produced, therefore;

1.00 moles of [tex]Fe_2O_3[/tex] reacts with:

[tex]=\dfrac{1.00 \ moles \times 1652 \ kJ}{2 \ moles}[/tex]

= 826 kJ of heat will be produced.

To the third question; we have:

How much heat is released when 1.60 g iron is reacted with excess O₂?

We need to find the number of moles of iron first.

We know that number of moles = mass/molar mass

Thus, the molar mass of iron = 55.8 g/mol

number of moles of iron = (1.60g) / (55.8 g/mol)

number of moles of iron = 0.02867 mol

Thus; [tex]\dfrac{0.02867\ mol \times 1652 \ kJ }{4 \ mol}[/tex]

= 11.84 kJ of heat is released.

The last question says:

How much heat is released when 11.8 g Fe and 1.20 g O₂ are reacted?

Again;

the number of moles of Fe = (11.8g) / (55.8 g/mol) = 0.2114 mole of Fe

Thus; [tex]\dfrac{0.2114\ mol \times 1652 \ kJ }{4 \ mol}[/tex]

= 87.31 kJ of heat is released.

On the other hand,

the number of moles of O₂ = (1.20g) / (32 g/mol) = 0.0375 mol of O₂

Thus; [tex]\dfrac{0.0375\ mol \times 1652 \ kJ }{3 \ mol}[/tex]

= 20.65 kJ of heat is released

Therefore, when these two(2) reactants reacted with each other, it is just the smaller amount of heat that would be released because oxygen tends to be the limiting reactant.

✅Paraphrasing and summarizing .✅

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Answer:

D. Limitations due to ethical concerns about experimental subjects.

Explanation:

Answer:

A

Explanation:

(its my friend)

Answer:

The block is made up of aluminum.

density = 2.7 g/cm³

Explanation:

Given data:

Dimension of metal block = 2.0 cm×2.5 cm× 3.0 cm

Mass of block = 40.05 g

Density of block = ?

Which metal is this = ?

Solution:

Density:

Density is equal to the mass of substance divided by its volume.

The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

Units:

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

D=m/v

D= density

m=mass

V=volume

Volume of block = 2.0 cm×2.5 cm× 3.0 cm = 15 cm³

d = m/v

d = 40.5 g/ 15 cm³

d = 2.7 g/cm³

The block is made up of aluminum.

Answer:

B is the correct answer because bubbling is a sign of chemical reaction and production of a new substance

Answer:

B

Explanation:

Just did it on usa test prep

The element which is most likely to be magnesium  is the element with the electronic configuration same as magnesium.

It is defined as a substance which cannot be broken down further into any other substance. Each element is made up of its own type of atom. Due to this reason all elements are different from one another.

Elements can be classified as metals and non-metals. Metals are shiny and conduct electricity and are all solids at room temperature except mercury. Non-metals do not conduct electricity and are mostly gases at room temperature except carbon and sulfur.

The number of protons in the nucleus is the defining property of an element and is related to the atomic number.All atoms with same atomic number are atoms of same element.

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Answer:

true i think

Explanation:

Answer:

KF

Explanation:

Potassium = K

Fluoride = F

[tex]K^{+1}F^{-1}K_{1} F_{1}=KF[/tex]

Answer:

KF is your answer. Can I get Brainliest

Answer:

Love it because Love it

Explanation:

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Answer:

There are three main types of rocks: sedimentary, igneous, and metamorphic. Each of these rocks are formed by physical changes—such as melting, cooling, eroding, compacting, or deforming—that are part of the rock cycle. Sedimentary Rocks Sedimentary rocks are formed from pieces of other existing rock or organic material. There are three different types of sedimentary rocks: clastic, organic (biological), and chemical. Clastic sedimentary rocks, like sandstone, form from clasts, or pieces of other rock. Organic sedimentary rocks, like coal, form from hard, biological materials like plants, shells, and bones that are compressed into rock. The formation of clastic and organic rocks begins with the weathering, or breaking down, of the exposed rock into small fragments. Through the process of erosion, these fragments are removed from their source and transported by wind, water, ice, or biological activity to a new location. Once the sediment settles somewhere, and enough of it collects, the lowest layers become compacted so tightly that they form solid rock. Chemical sedimentary rocks, like limestone, halite, and flint, form from chemical precipitation. A chemical precipitate is a chemical compound—for instance, calcium carbonate, salt, and silica—that forms when the solution it is dissolved in, usually water, evaporates and leaves the compound behind. This occurs as water travels through Earth’s crust, weathering the rock and dissolving some of its minerals, transporting it elsewhere. These dissolved minerals are precipitated when the water evaporates. Metamorphic Rocks Metamorphic rocks are rocks that have been changed from their original form by immense heat or pressure. Metamorphic rocks have two classes: foliated and nonfoliated. When a rock with flat or elongated minerals is put under immense pressure, the minerals line up in layers, creating foliation. Foliation is the aligning of elongated or platy minerals, like hornblende or mica, perpendicular to the direction of pressure that is applied. An example of this transformation can be seen with granite, an igneous rock. Granite contains long and platy minerals that are not initially aligned, but when enough pressure is added, those minerals shift to all point in the same direction while getting squeezed into flat sheets. When granite undergoes this process, like at a tectonic plate boundary, it turns into gneiss (pronounced “nice”). Nonfoliated rocks are formed the same way, but they do not contain the minerals that tend to line up under pressure and thus do not have the layered appearance of foliated rocks. Sedimentary rocks like bituminous coal, limestone, and sandstone, given enough heat and pressure, can turn into nonfoliated metamorphic rocks like anthracite coal, marble, and quartzite. Nonfoliated rocks can also form by metamorphism, which happens when magma comes in contact with the surrounding rock. Igneous Rocks Igneous rocks (derived from the Latin word for fire) are formed when molten hot material cools and solidifies. Igneous rocks can also be made a couple of different ways. When they are formed inside of the earth, they are called intrusive, or plutonic, igneous rocks. If they are formed outside or on top of Earth’s crust, they are called extrusive, or volcanic, igneous rocks. Granite and diorite are examples of common intrusive rocks. They have a coarse texture with large mineral grains, indicating that they spent thousands or millions of years cooling down inside the earth, a time course that allowed large mineral crystals to grow.

Alternatively, rocks like basalt and obsidian have very small grains and a relatively fine texture. This happens because when magma erupts into lava, it cools more quickly than it would if it stayed inside the earth, giving crystals less time to form. Obsidian cools into volcanic glass so quickly when ejected that the grains are impossible to see with the naked eye. Extrusive igneous rocks can also have a vesicular, or “holey” texture. This happens when the ejected magma still has gases inside of it so when it cools, the gas bubbles are trapped and end up giving the rock a bubbly texture. An example of this would be pumice.

Explanation:

oh and also nice profile pic :P

Answer:

See explanation

Explanation:

DDT is dichlorodipphenylrtrichloroethane. It is was a popular insecticide used for agricultural purposes. Racheal Carson's book, silent springs drew attention to the use of insecticides such as DDT in agriculture.

DDT is a non-biodegradable, fat-soluble compound. It enters into the food chain and has the ability to bioaccumulate in the human body where it becomes deposited in the adipose tissue.

There is no direct harmful effect of DDT to humans, however, when oxidation of DDT takes place in body many harmful metabolites  are released into the body causing harmful effects to human health such as; breast cancer, male infertility, miscarriages and low birth weight, developmental delay and liver damage.

There is convincing empirical evidence supporting the carcinogenicity of DDT its main metabolites DDE and DDD, however, many studies on the harm caused by DDT and its main metabolites in the body have so far led to inconclusive, and sometimes negative, results

Answer:

The answer is option D 3

Explanation:

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Answer:

d.3

Explanation:

Answer:

D. A neap tide is the period halfway between tides when the tide changes direction. (correction) Answer : C

Explanation:

Process of elimination can be used. First off, A is incorrect because neap tides have the smallest tidal range ; spring tides would fit this choice. B is incorrect since neap tides are specific to the first, and third quarter moons when the sun and moon are right angles. C is wrong because it is the other way around since high tides are a little higher than average and low tides are a little lower than average (correction) this is correct since higher low tides and lower high tides are closer together and have a smaller tidal range than standard tides(spring tides) with higher high tides, and lower low tides. D is correct because they occur halfway between the spring tides (correction): incorrect since a neap tides occur around a week(7 days) after a spring tide(moderate tides). There is no evidence this is true.

There are three patterns: diurnal(one high and low tides a day), semidiurnal(two high and low tides a day), and mixed(two high and low tides a day of different lengths).

The spring and neap tides are the types of tides involved with the low and high tides.

Answer:

T₂ =  344.8 K

Explanation:

Given data:

Initial volume of gas = 475 cm³

Initial temperature = 273 K

Final volume = 600 cm³

Final temperature = ?

Solution:

The given problem will be solve through the Charles Law.

According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.

Mathematical expression:

V₁/T₁ = V₂/T₂

V₁ = Initial volume

T₁ = Initial temperature

V₂ = Final volume  

T₂ = Final temperature

Now we will put the values in formula.

V₁/T₁ = V₂/T₂

T₂ = T₁V₂/V₁  

T₂ = 273 K × 600 cm³ /  475 cm³

T₂ = 163800K . cm³ / 475 cm³

T₂ =  344.8 K

Answer:

Be: Helium--------Loses-------4--------Be2+

B: Helium--------Loses--------5--------B5

N: Helium--------Gain---------7--------N3−

O: Lithium---------Gain--------8-------O2−

F: Neon--------electrically neutral-------9---------F-

Explanation:

Hope this helps:)

Answer:

Radioactive elements

Explanation:

Answer: false 100

Explanation:

if this is the true or false test here