A particular element exists in two stable isotopic forms. One isotope has a mass of 78.9183 amu (50.69% abundance). The other isotope has a mass of 80.9163 amu (49.31% abundance). Calculate the average mass of the element and determine its identity.

Answer:

electron-electron repulsion

Explanation:

When electrons add into valence shell of neutral elements, the element assumes a negative oxidation state. With this, the number of electrons having (-) charges will be larger than the number of protons having positive (+) charges. As a result, the extra electrons repel one another (i.e., like charges repel) and a larger radius is the result.  

In contrast, when cations are formed, electrons are removed from the valence level (oxidation) producing an element having a greater number of protons than electrons. The larger number of protons will function to attract the electron cloud with a greater force that results in a contraction of atomic radius and a smaller spherical volume than the neutral unionized element.    

To visualize, see attached chart that shows atomic and ionic radii before and after ionization of the elements.  

Explanation:

4.92*10-3=4.92/10^3=

4.92/1000=0.00492

Answer:

0.2moles

Explanation:

Given parameters:

 Number of molecules of H₂ = 1.8 x 10²³molecules

Unknown:

Number of moles of NH₃ = ?

Solution:

 The reaction equation is given as:

                 N₂  + 3H₂   →   2NH₃

   Let us solve from the known to the unknown specie;

 Since the number of molecules is 1.8 x 10²³molecules of H₂;

      6.02 x 10²³molecules will give 1 mole of a substance

      1.8 x 10²³molecules will produce  [tex]\frac{1.8 x 10^{23} }{6.02 x 10^{23} }[/tex] mole of H₂

                                                               = 0.3moles of H₂

From the balanced chemical equation;

                 3 moles of H₂ produced 2 moles of NH₃

                 0.3 moles of H₂ will yield [tex]\frac{0.3 x 2}{3}[/tex]   = 0.2moles

Answer:

Percent yield of CO₂ is 6.25 %.

Explanation:

Given data:

Percent yield of CO₂ = ?

Actual yield of CO₂ = 28.16 g

Number of moles of C₈H₁₈ = 8.000 mol

Number of moles of O₂ = 16.00 mol

Solution:

Chemical equation:

2C₈H₁₈ + 25O₂  →  16CO₂ + 18H₂O

Now we will compare the moles of C₈H₁₈ and O₂  with CO₂.

                 C₈H₁₈            :          CO₂

                    2                :             16

                  8.000          :            16/2×8.000 = 64 mol

                   O₂               :             CO₂

                    25              :              16

                     16              :              16/25×16= 10.24 mol

Less number of moles  of CO₂ are produced from 16 moles of O₂. it will limit the yield of CO₂.

Grams of CO₂ produced:

Mass = number of moles × molar mass

Mass = 10.24 mol  × 44 g/mol

Mass = 450.56 g

Percentage yield of CO₂:

Percentage yield = actual yield / theoretical yield × 100

Percentage yield = 28.16 g/ 450.56 g× 100

Percentage yield = 6.25 %

Answer:

Option B is correct.

4

Explanation:

We know that an atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.

All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example, if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.

In given problem we are given with 2 neutrons of helium. We know that the atomic number of He is 2. Thus Mass number of He is,

Number of neutrons + number of proton

2 + 2 = 4

Thus, option B is correct.

Answer:

ionization energy and electronegativity

Explanation:

A: Xylem transports and stores water and water-soluble nutrients in vascular plants. Phloem is responsible for transporting sugars, proteins, and other organic molecules in plants.

Answer:

Explanation:

The force acting on an object can be found by using the formula

From the question

mass = 70 kg

acceleration = 4 m/s²

We have

force = 70 × 4

We have the final answer as

Hope this helps you

Answer:

Waste.

Explanation:

"A major environmental concern related to nuclear power is the creation of radioactive wastes such as uranium mill tailings, spent (used) reactor fuel, and other radioactive wastes. These materials can remain radioactive and dangerous to human health for thousands of years. Radioactive wastes are subject to special regulations that govern their handling, transportation, storage, and disposal to protect human health and the environment. The U.S. Nuclear Regulatory Commission (NRC) regulates the operation of nuclear power plants."

Answer:

the melting point is 1431 degrees f or 777.2 c

Answer:

1,431° Fahrenheit or 777° Celsius

Answer:

ipfiyf8y97guog7

Explanation:

oyviyvhlvoyvhlvouuoupvpu

Answer:

B

Explanation:

Valence electrons are the number of electrons out the outermost shell of the diagram. In this diagram, there is one valence electron. This means that it is highly reactive since the shell is not complete and needs other elements to be able to complete the outermost shell. If this model had a full outermost shell, then it would not be reactive (noble gases).

In the Bohr model of an atom,  the element that this model represents is highly reactive because the model is showing only one valence electron.

To ascertain how reactive an element is, we have to look at its valence shell. In the Bohr model, electrons are arranged around the nucleus in shells.

If we look at the model shown, the valence (outermost) shell has only one electron which is easily lost.

This model corresponds to a highly reactive group 1 alkali metal.

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Answer:

9.75564x10^21

Explanation:

Moles of MgBr2=Mass/Molar Mass

=1.50grams/184.113g/mol

=0.0081mol(because the grams cancel out)

2 x 0.0081mol= 0.0162mol

0.0162 x 6.022 x 10^23(because avogadro's #)= 9.75564x10^21

hope this helps!!

9.75564x10^21  anions are there in 1.50 g of MgBr2

Cations and anions are both ions, the cation are negatively charges ions where as anions are positively charged ions.

These ions are atoms or molecules either gain or loss of one or more valence electrons, giving the ion a net positive or negative charge.

If the chemical species has more protons than electrons, it carries a net positive charge. If there are more electrons than protons, the species has a negative charge. The number of neutrons determines the isotope of an element but does not affect the electrical charge.

Cations with a net positive charge like Silver Ag+, Hydronium: H3O+, Ammonium: NH4+ where as Anions  with a net negative charge Hydroxide anion: OH-, Oxide anion: O2-, Sulfate anion:SO42-.

Moles of MgBr2=Mass/Molar Mass

=1.50grams/184.113g/mol

=0.0081mol(because the grams cancel out)

2 x 0.0081mol= 0.0162mol

0.0162 x 6.022 x 10^23= 9.75564x10^21

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Answer:

Another word for vapor is gas.

Answer:

Another name for vapour is gas

Mass of products is exactly equal to mass of reactants. A mole-mole factor is a ratio of the moles for any two substances in an equation.

The law of mass of conservation states that the the mass of the reactant is exactly equal to the mass of the product.

According to this law, matter can be neither created nor be destroyed.  The mass of collection of objects never changes, no matter how the parts are rearranged.

To calculate the amount of atoms that are reacting, and they always be the same as the product because the law of conservation states that no matter can be formed or destroyed, as transferred.

Thus, the amount of reactants and products in a chemical reaction is calculated by the law of mass of conservation.

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Answer:

every living thing

Explanation:

its right

Answer:

Everything is made up of cells

Explanation:

Humans, animals, plants, etc.

Answer:

the answer would be 0.666 mL

Explanation:

10g is 66% of 15g

The empirical formula for the hydrogen crystal is CaBr2H3.

To calculate the formula for the hydrogen crystal, we need to determine the number of moles of each element present in the given substances (CaBr2 and H2O).

Let's start by calculating the number of moles of calcium bromide (CaBr2):

Molar mass of CaBr2 = (40.08 g/mol) + (2 * 79.90 g/mol) = 199.88 g/mol

Number of moles of CaBr2 = Mass of CaBr2 / Molar mass of CaBr2

= 7.58 g / 199.88 g/mol

≈ 0.0379 mol

Next, we calculate the number of moles of water (H2O):

Molar mass of H2O = (2 * 1.01 g/mol) + 16.00 g/mol = 18.02 g/mol

Number of moles of H2O = Mass of H2O / Molar mass of H2O

= 0.918 g / 18.02 g/mol

≈ 0.051 mol

Now, we need to determine the mole ratio between hydrogen (H) and the other elements in the crystal. Since hydrogen is present only in water, and the ratio of hydrogen to oxygen in water is 2:1, we can conclude that the number of moles of hydrogen is twice the number of moles of water:

Number of moles of hydrogen = 2 * Number of moles of H2O

≈ 2 * 0.051 mol

≈ 0.102 mol

To find the formula for the hydrogen crystal, we compare the number of moles of hydrogen (0.102 mol) to the number of moles of calcium bromide (0.0379 mol).

Since the number of moles of hydrogen is greater than the number of moles of calcium bromide, the simplest whole number ratio can be obtained by dividing both values by the number of moles of calcium bromide:

0.102 mol / 0.0379 mol ≈ 2.69

Rounding this value to the nearest whole number, we get:

2.69 ≈ 3

Therefore, the empirical formula for the hydrogen crystal is CaBr2H3.

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Answer:

Pressure goes up

Explanation:

The pressure is inversely proportional to the volume.  So when volume is decreased the pressure rises.

The molecules are getting pushed closer together and more collisions occur which will also increase the temperature.

Answer:

Ions are formed by the addition of electrons to, or the removal of electrons from, neutral atoms or molecules or other ions; by combination of ions with other particles; or by rupture of a covalent bond between two atoms in such a way that both of the electrons of the bond are left in association with one of the

Explanation:

hope this helps

Answer:

Ion, any atom or group of atoms that bears one or more positive or negative electrical charges. Positively charged ions are called cations; negatively charged ions, anions. Ions are formed by the addition of electrons to, or the removal of electrons from, neutral atoms or molecules or other ions; by combination of ions with other particles; or by rupture of a covalent bond between two atoms in such a way that both of the electrons of the bond are left in association with one of the formerly bonded atoms.

Explanation:

Examples of these processes include the reaction of a sodium atom with a chlorine atom to form a sodium cation and a chloride anion; the addition of a hydrogen cation to an ammonia molecule to form an ammonium cation; and the dissociation of a water molecule to form a hydrogen cation and a hydroxide anion.

Answer:

Xe

Explanation:

noble gas is in the last column of the periodic table.

Zr is in Period 5

Answer:b

Explanation:

Answer:

its mineral composition

Explanation:

The atomic bonds within a mineral generally determine which wavelengths of light will be absorbed and which will be reflected. Those wavelengths that are reflected back to our eyes determine the color of the mineral. Some minerals have free electrons that will absorb certain wavelengths of light.

Mineral composition is the property of a rock that determines it's color.

A rock is a naturally occurring solid that comprises of different minerals or substances which fuses together or solidified together to form a very big solid mass.

Therefore, Mineral composition is the property of a rock that determines it's color.

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The answer is A, to my brain power ig B)

Chemical weathering is the decomposition of rocks and minerals by chemical means. Dissolving limestone by acid rain is an example of chemical weathering. Hence, option A is correct.

Weathering is the process of decomposition of rocks and minerals in the earth by some physical or chemical factors. Weathering by heat, pressure and wind are called physical weathering.

Reaction with acids, water or air also lead to weathering of rocks. The chemical reaction taking place there can decompose the rock and form new products make cracks and color changes in the rocks.

Lime stones are made of calcium carbonate. When limestone reacts with an acid , it decomposes into its salt and carbon dioxide. Therefore, it is an example of chemical weathering. Hence, option A is correct.

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Answer:

3.00 g/mL

Explanation:

Step 1: Given data

Mass of the baseball (m): 1500 g

Volume of the baseball = Volume of water displaced (V): 500 mL

Density of the baseball (ρ): ?

Step 2: Calculate the density of the baseball

The density is equal to the mass divided by the volume.

ρ = m/V

ρ = 1500 g/500 mL

ρ = 3.00 g/mL

Answer: 120.9 grams

Explanation:

Given the question : How many grams are in 3.67 moles of Lithium cyanide?

Chemical formula of lithium cyanide = LiCN

Molar mass of LiCN: Li = 6.941 ; C = 12, N = 14

LiCN = (6.941 + 12 + 14). = 32.941 g/mol

(Gram of substance / mole of substance) = (molar mass of substance / one mole)

(Gram of substance / 3.67) = (32.941 / 1)

= gram * 1 = 3.67 * 32.941

Gram of substance = 120.89347

= 120.9 grams

Answer:

Explanation:

The equations in each option are confusing (repeated) but understandable

Balancing a chemical equation means the same number of individual and overall atoms on the reactant side is equal to the same number of individual and overall atoms on the product side. This is based on the law of conservation of matter which states that matter can neither be created nor destroyed, hence the no atom must be unaccounted for on any side.

The balancing of these equations seem to test the knowledge of a particular trick in balancing of equation - which will be highlighted as the equation is balanced

(a) To balance

SiO₂(s) + C(s) ⇒ Si(s) + CO(g)

The balanced equation will be

SiO₂(s) + 2C(s) ⇒ Si(s) + 2CO(g)

NOTE: The best way to address equations like this to balance the uniatomic element last.

(b) SiCl₄(l) + Mg(s) ⇒ Si(s) + MgCl₂(s)

The balanced equation will be

SiCl₄(l) + 2Mg(s) ⇒ Si(s) + 2MgCl₂(s)

NOTE: As noted earlier, the uniatomic  molecule should be balanced last

(c) To balance

Na₂SiF₆(s) + Na(s) ⇒ Si(s) + NaF(s)

The balanced equation will be

Na₂SiF₆(s) + 4Na(s) ⇒ Si(s) + 6NaF(s)

NOTE: As noted earlier, the uniatomic  molecule should be balanced last

Please, always sum the number of individual and overall atoms on both sides when you are done answering questions like this just to be sure.

Answer:B: data verified by other studies

             C:data provided by an ice cream manufacturer

             E: data provided by an ice cream manufacturer

Answer:

the answer is A,B,E

Explanation:

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