why is calcuim (ca) in group 2. period 4 on the periodic table

Answer:

\(2.26 \times 10^{23}atomsF\)

Explanation:

Step 1: Given data

Step 2: Convert "V" to liters

We will use the conversion factor 1 L = 1000 mL.

750.0 mL × 1 L/1000 mL = 0.7500 L

Step 3: Calculate the moles of HF

We will use the following expression.

n = M × V

n = 0.500 mol/L × 0.7500 L = 0.375 mol

Step 4: Calculate the atoms of F in 0.375 moles of HF

We will use the following relationships:

\(0.375 mol HF \times \frac{1 mol F}{1 molHF} \times \frac{6.02 \times 10^{23}atomsF }{1 mol F} = 2.26 \times 10^{23}atomsF\)

Answer:

V₂ = 25.065 L

Explanation:

Given data:

Initial volume = 15L

Initial pressure = 1500 mmHg (1500/760 = 1.97 atm)

Initial temperature = 299 K

Final temperature = 350 K

Final volume = ?

Final pressure = 1050 mmHg (1050/760 = 1.38 atm)

Formula:

P₁V₁/T₁ = P₂V₂/T₂  

P₁ = Initial pressure

V₁ = Initial volume

T₁ = Initial temperature

P₂ = Final pressure

V₂ = Final volume

T₂ = Final temperature

Solution:

V₂ = P₁V₁ T₂/ T₁ P₂  

V₂ = 1.97 atm × 15 L × 350 K / 299 K × 1.38 atm

V₂ = 10342.5 atm .L. K / 412.62 K.atm

V₂ = 25.065 L

While tumor marker test results can be useful, they are not conclusive. A low result does not imply that you do not have cancer or that you are in remission.

CA 15-3, for example, is raised in less than half of patients with early breast cancer and in more than 80% of those with metastatic breast cancer. Three tumor markers, cancer antigen 15-3 (CA 15-3), cancer antigen 27.29 (CA 27.29), and carcinoembryonic antigen (CEA), have been used in breast cancer care to help monitor metastatic breast cancer (advanced disease), but they have not been found to be useful in detecting a breast cancer recurrence or extending lives. If the level falls, the treatment is effective. If it rises, the cancer may be spreading.

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Answer:

3.6124 m/kg

Explanation:

Molality is calculated as moles of solute (mol) divided by kilogram of solvent (kg). Here, we can find these numbers by using the 35.4%, which gives us  35.4 g of H3PO4 and 100 g of solution to work with.

To go from grams to moles for the phosphoric acid, you need to find the molar mass of the compound or element and divide the grams of the compound or element by that molar mass.

Here, the molar mass for phosphoric acid is 97.9952 g/mol. The equation would look like this:

35.4 g x 1 mol / 97.9952 g = 0.3612422 mol

Next, the 100 g of solvent can easily be converted to 0.1 kg of solvent.

To find the molality, divide the moles of solute and kilograms of solution.

0.3612422 mol / 0.1 kg = 3.6124 m/kg

Yes because it can produce unlike nonliving organism

Answer:

Charles Darwin, in full Charles Robert Darwin, (born February 12, 1809, Shrewsbury, Shropshire, England—died April 19, 1882, Downe, Kent), English naturalist whose scientific theory of evolution by natural selection became the foundation of modern evolutionary studies.

Charles Darwin's theory of evolution states that evolution happens by natural selection. Individuals in a species show variation in physical characteristics. ... As a consequence those individuals most suited to their environment survive and, given enough time, the species will gradually evolve.

Explanation:

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Answer: sand paper against wood

Explanation:

In the given reaction, the limiting reactant is C₆H₆ (benzene).

To determine the limiting reactant as well as calculate the mass of HCl produced, compare the moles of each reactant.

The number of moles for each reactant:

Molar mass of Cl₂ = 35.5 g/mol + 35.5 g/mol = 71 g/mol

Moles of Cl₂ = mass of Cl₂ / molar mass of Cl₂

                     = 45 g / 71 g/mol

                     = 0.634 moles of Cl₂

Molar mass of C₆H₆ (benzene) = 12 g/mol + 6(1 g/mol) = 78 g/mol

Moles of C₆H₆ = mass of C₆H₆ / molar mass of C₆H₆

                        = 45 g / 78 g/mol = 0.577 moles of C₆H₆

Determine the stoichiometry between Cl₂ and HCl:

Cl₂ + C₆H₆ → C₆H₅Cl + HCl

Here, we can see that 1 mole of Cl₂ produces 1 mole of HCl.

Thus, the limiting reactant is C₆H₆ (benzene).

Calculate the mass of HCl produced:

Molar mass of HCl = 1 g/mol + 35.5 g/mol = 36.5 g/mol

Moles of HCl produced = moles of C₆H₆ = 0.577 moles

Mass of HCl produced = moles of HCl produced × molar mass of HCl

Mass of HCl produced = 0.577 moles × 36.5 g/mol

                                     ≈ 21.04 g

Therefore, approximately 21.04 grams of HCl will be produced.

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Rutherford observed that not all of the alpha particles were absorbed by the gold foil. Few alpha particles are scattered with deflection. This surprised him.

Rutherford was surprised to observe that most of the alpha particles he fired at the gold foil went straight through the foil with little deflection. He expected that the alpha particles would be strongly deflected by the positively charged nucleus of the atoms in the gold foil.

It was a famous experiment done by Rutherford in which he bombarded a thin sheet of gold with alpha particles. He observed that most of the particles passed through the sheet, but a few were scattered at large angles. From this, he concluded that the atom was mostly empty space with a small, dense, positively charged nucleus.

This experiment is called the alpha particle scattering experiment and through this experiment, he was able to discover the nucleus.

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The relationship between the rate of diffusion r, and d is r ∝ 1/√d.

The relationship between the rate of diffusion (r) and the density of a gas (d) can be explained using Graham's law of diffusion. According to this law, the rate of diffusion of a gas is inversely proportional to the square root of its density. Mathematically, it can be expressed as:

r ∝ 1/√d

where the symbol '∝' represents 'proportional to'. The constant of proportionality (k) can be introduced to this equation as:

r = k/√d

This equation shows that as the density of a gas increases, its rate of diffusion decreases. This is because denser gases have more molecules per unit volume and thus, they experience greater intermolecular collisions that hinder their movement. Therefore, it requires more energy for them to diffuse through a medium compared to less dense gases.

The relationship between the rate of diffusion and density is particularly important in understanding the behavior of gases in different environments. For instance, in a gas chromatography column, the rate of diffusion of a gas determines how quickly it moves through the column and separates from other components. Similarly, in the Earth's atmosphere, the rate of diffusion of greenhouse gases such as carbon dioxide affects their concentration and hence, their impact on climate change.

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With a half life of 28.8 years, 1g of strontium-90 to decay to 125mg take 28.8 years.

Half life is defined as the amount of time it takes for a radioactive substance or half its atoms to break down or change. Half-lives can last anywhere between a nanosecond and a billions of years.

The decimal percentage remaining

= 125 / 1 = 125

(1/2)ⁿ = 125

n log 1 = log 125

n = log 125 / log 1

n = 2.09 / 0

n = 0

The decay = 28.8 x 0

The decay = 28.8 year.

Thus, with a half life of 28.8 years, 1g of strontium-90 to decay to 125mg take 28.8 years.

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Answer:

\(\boxed {\boxed {\sf Mass \ of \ products \ = \ mass \ of \ reactants}}\)

Explanation:

The Law of Conservation of Mass states that mass cannot be created or destroyed.

In a chemical reaction, there are products and reactants. The reactants react and produce the products.

Since mass can't be created or destroyed, the mass of the products must be equal to the mass of the reactants if mass was conserved in a chemical reactions.

Answer: Chemical change

Explanation: Chemical change because when you add baking soda, a chemical reaction is happening. I hope this helps :)

Answer:

a

Explanation:

Answer:

32.52×10¹⁹ atoms

Explanation:

Given data:

Mass of gold = 0.106 g

Number of atoms of gold = ?

Solution:

We will calculate the number of moles first.

Number of moles = mass/molar mass

Number of moles = 0.106 g/ 197 g/mol

Number of moles = 5.4×10⁻⁴ mol

Number of atoms:

1 mole contain 6.022×10²³ atoms

5.4×10⁻⁴ mol ×  6.022×10²³ atoms /1 mol

32.52×10¹⁹ atoms

Answer:

why are people s opinions and prejudices her greatest obstacles

1. The products in this reaction are AlCl₃(aq) and H₂(g).

2. The reactants in this reaction are Al(s) and HCl(aq).

3. The balanced equation is 2Al(s) + 6HCl(aq) → 2AlCl₃(aq) + 3H₂(g)

4. This is a single displacement reaction.

5. The symbols indicate the physical states of the reactants and products.

A single displacement reaction, also known as a single replacement reaction, is a type of chemical reaction in which an element or ion in a compound is replaced by another element or ion.

In a single displacement reaction, one reactant is usually an element in its elemental state, while the other reactant is a compound.

In the given reaction,  "Al(s)" means solid aluminum, "HCl(aq)" means hydrochloric acid dissolved in water (aq means aqueous), "AlCl₃(aq)" means aluminum chloride dissolved in water, and "H₂(g)" means hydrogen gas.

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Answer:

6.022 x 10^23 particles

Explanation:

Chemists have chosen to count atoms and molecules using a unit called the mole (mol), from the Latin moles, meaning “pile” or “heap.”

One mole is 6.022 x 10^23 of the microscopic particles which make up the substance in question.

Hope this helped! :^)

Answer: The empirical formula of the metal sulfide is \(CoBr_{2}\).

Explanation:

Given: Mass of metal = 20.38 g

Mass of metal sulfide = 31.47 g

Moles is the mass of a substance divided by its molar mass.

So, moles of cobalt (molar mass = 59 g/mol) are as follows.

\(Moles = \frac{mass}{molarmass}\\= \frac{20.38 g}{59 g/mol}\\= 0.345 mol\)

Moles of bromine (molar mass = 80 g/mol) are as follows.

\(Moles = \frac{(31.47 - 20.38) g}{80 g/mol}\\= \frac{11.09 g}{80 g/mol}\\= 0.138 mol\)

Now, the ratio of number of moles of cobalt and number of moles of bromine are as follows.

Moles of Co : Moles of Br = 1 : 2

Hence, the empirical formula is \(CoBr_{2}\).

Thus, we can conclude that the empirical formula of the metal sulfide is \(CoBr_{2}\).

Answer:

1. 25.19

2. 301.57

Explanation:

it says it's correct...

The conversion of units of temperatures from one scale to the other which is measure by Carla and Maurice are given as.

298.34 K = 25.34°C

28.42°C = 301.42 K

The temperature can be measure by using three units.

Relationship between Kelvin (K) and Celsius (°C)

Let the value of temperature in Celsius (°C)  unit as X °C, then value of this temperature in  Kelvin (K) is,

X °C = 273 + X °C = (273 + X) K

Let the value of temperature in Kelvin (K) as Y K , then value of this temperature in Celsius (°C) is,

Y K =  Y K - 273 = (Y - 273) °C

If 298.34 K

Then 298.34 K = 298.34 K - 273 = 25.34°C

If 28.42°C

Then, 28.42°C =  273 + 28.42°C = 301.42 K

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The volume of the gold plates in cm₃ is 2.513274 cm₃

Volume is the space occupied by a three-dimensional object“”

Volume = {mass} {density}

Given that the thickness or height of medallion, h = 2 mm = 0.2 cm

Diameter of the medallion, d = 4 cm

Radius of medallion, r = d/2 = 2 cm⁻³

The thickness of the gold plating, x = 1 μm = 10⁻⁴ cm

The density of gold = 19.3 g cm

Now we know that the shape of a medallion is cylindrical.

Hence, the volume of the medallion before platting,

Vbefore = π.r2.h = π.(2)2.0.2 = 2.513274 cm₃

Therefore, the volume of the gold-plated is 2.513274 cm₃.

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One of the most extensively researched areas of homogeneous catalysis is homogeneous hydrogenation. These investigations' findings have proven to be crucial for comprehending the fundamental ideas behind how transition metal complexes activate tiny molecules.

Homogeneous hydrogenation has been widely used in organic chemistry during the past three decades, including the manufacture of significant medicines, particularly in situations where a high level of selectivity is required.This book provides an overview of the fundamental ideas and practical uses of transition metal complex-mediated homogeneous hydrogenation. The methods by which these activities take place are given special consideration, and the function of the recently found complexes of molecular hydrogen is outlined. Other than H2 sources of hydrogen are also taken into consideration (transfer hydrogenation).

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Answer:

0.26 moles........................

This shows that the process is exothermic and that heat energy is released.

The dissolution of ammonium nitrate, \(NH_4NO_3\), can be represented by the following equation:

\(NH_4NO_3 (s) \rightarrow NH_4^{+}(aq) + NO_3^{-} (aq)\)

The dissolution of ammonium nitrate in water results in the formation of its constituent ions, ammonium (\(NH_4^+\)) and nitrate (\(NO_3^{-}\)). This process is exothermic, meaning that it releases energy in the form of heat. This process is used in chemical “ice packs” for first aid as the release of energy cools the surrounding area.

The reaction pathway diagram for this process is shown below. The reactant is ammonium nitrate (\(NH4NO_3\)) and the products are ammonium ion (\(NH_4^+\)) and nitrate ion (\(NO_3^{-}\)). The ΔH (enthalpy) of the reaction is represented by the downward-pointing arrow. This indicates that the reaction is exothermic, releasing energy in the form of heat.

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complete question:The dissolution of ammonium nitrate, NH4NO3, is represented by the equation

NH4NO3 (s) → NH4+(aq) + NO3 – (aq)

One common use of this process is in chemical “ice packs” for first aid for injuries. Water is mixed with solid ammonium nitrate, NH4NO3, when the inside pouch of the “ice pack “is broken. This results in the “ice pack” getting cold enough to cool injured muscles or joints. Using this information, please complete the reaction pathway diagram shown below. Label the products and ΔH.

Answer:

17.8ml-15.6ml is 2.2 ml then convert to cm so 2.2cm^3

Answer:

I think it's b probably wrong

True;

The earth is currently in an interglacial period

Climate has changed naturally over the earth's history

False

The increase since 1860 is similar to previous increases

Atmospheric composition have remained the same throughout earth history.

Atmospheric carbon dioxide has increased significantly since 1860, primarily due to human activities such as burning of fossil fuels and deforestation.

There are also seasonal variations in CO2 concentrations, with higher concentrations in the winter months and lower concentrations in the summer months. This is because the majority of the world's vegetation is in the Northern Hemisphere, and during the winter months, there is less photosynthesis occurring to remove CO2 from the atmosphere.

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Answer:

pH = 1.05

Explanation:

A solution of sulfuric acid, H₂SO₄, dissociates in water as follows:

H₂SO₄ → 2H⁺ + SO₄²⁻

That means per mole of H₂SO₄ you will have 2 moles of H⁺

pH = -log [H⁺]

As [H₂SO₄] = 0.045M and [H⁺] = 2×[H₂SO₄]

[H⁺] = 0.090M

pH = -log [0.090M]

Answer:

Ethanol

Explanation:

Solvent extraction is the process in which a compound transfers from one solvent to another owing to the difference in solubility or distribution coefficient between these two solvents(Science Direct).

We have to remember that oxalic acid will be extracted better into a solvent in which it is more soluble. From the data given; oxalic acid is more soluble in ethanol than in ether.

This simply means that ethanol is a better solvent for extracting oxalic acid  from water when compared to ether.