What causes a substance to not be able to be broken down by chemical change?

The answer is 8.13 x 10²⁸ atoms.

First we calculate  the number of moles using the molar mass.

molar mass of helium = 4 g/mol. 

it means that 1 mole of helium atoms weighs 4 gram.

Now we have 540 kg of helium =540000 grams

Number of moles in 540000 grams;

540000 / 4 =135000 mol

Now in one mole there is 6.02 x 10²³ atoms

So, in 135000 mol there is;

135000 x 6.02 x 10²³  = 8.13 x 10²⁸atoms

The answer is :

H2

because a compound is made up of 2 or more elements.

Explanation:

An element is a substance that is made uniquely from one type of atom. For example, the element hydrogen is produced from atoms comprising a single proton and a single electron. If you change the number of protons an atom has, you develop the type of element it is.

Answer:

H₂ can be classified as an element.

Explanation:

An element is defined as a substance with only one kind of atom.

H₂ is a substance that only has one kind of atom: hydrogen.

NO₃ is a substance that has two kind of atoms: nitrogen and oxygen.

NaCl is a substance that also has two kind of atoms: sodium and chlorine.

H₂SO₄ is a substance that has three kind of atoms: hydrogen, sulphur and oxygen.

Thus, H₂ can be classified as an element.

I hope it helps!

The mass number of an atom with 82 protons and 125 neutrons is 207. The mass number is calculated by adding the number of protons and neutrons, not considering electrons because they are much lighter and don't contribute significantly to an atom's mass. The atom described is a positively charged ion due to the imbalance between protons and electrons.

An atom with 82 protons, 125 neutrons, and 78 electrons will have a mass number of the sum of its protons and its neutrons. The mass number won't include the number of electrons because electrons are much lighter and do not significantly contribute to the total mass of an atom.

Therefore, the mass number of an atom with 82 protons and 125 neutrons is 82 + 125 = 207.

This atom would be an ion because the number of protons (which define the atomic number) and electrons are not equal. In this case, the atom has more protons than electrons, so it's a positively charged ion.

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The hydrogen bonds are completely destroyed and their number reduces in a particular volume of water as water molecules are heated up.

The interactions between neighbouring molecules of water containing one hydrogen and two oxygen atoms are the hydrogen bonds of water.

In all its 3 states, water has totally different chemical characteristics. This is due to hydrogen bonding between molecules of water. In a liquid state, hydrogen bonds are constantly formed and broken due to high kinetic energy. The kinetic energy is high due to the moderately high temperature of liquid water.

When the temperature of the water is raised further, the kinetic energy of the molecules of water will also increase. At a high value of kinetic energy, the speed of motion of water molecules will also be extremely high resulting in the breaking of hydrogen bonds.

At a particular increase in the temperature, all the hydrogen bonds between the water molecules will be broken and water will turn to steam. This temperature is called the boiling point of water.

Therefore, the hydrogen bonds are broken and their amount is reduced when the temperature of the water is increased.

Read more about hydrogen bonds, here

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Final answer:

An ionic bond is a chemical bond formed by the complete transfer of one or more electrons from one atom to another, resulting in the formation of oppositely charged ions that are held together by electrostatic forces.

Explanation:

An ionic bond is c. a chemical bond formed by the transfer of one or more electrons from the outermost energy level (the valance shell) of one atom to that of the other. This process results in the formation of oppositely charged ions: one atom becomes a positively charged cation due to the loss of electrons, while the other becomes a negatively charged anion from gaining those electrons. The attraction between these oppositely charged ions holds them together in an ionic compound.

Unlike covalent bonds, where electrons are shared between atoms, ionic bonds involve a complete transfer of one or more valence electrons to achieve a full outer shell, making the atoms involved more stable. Ionic bonds typically form between metals and non-metals, where metals tend to lose electrons, and non-metals tend to gain them, resulting in the characteristic ionic bond formation.

An ionic bond is formed by the transfer of electrons from one atom to another, creating charged ions that attract each other due to electrostatic forces. It typically occurs between metals and nonmetals. In contrast, covalent bonds involve the sharing of electron pairs between atoms.

An ionic bond is a type of chemical bond characterized by the transfer of electrons from one atom to another. This process results in the creation of oppositely charged ions: the atom that loses one or more electrons becomes a positively charged cation, while the atom that gains electrons becomes a negatively charged anion. The resulting electrostatic attraction between these oppositely charged ions forms the ionic bond. Ionic bonding typically occurs between metals and nonmetals, as metals tend to lose electrons while nonmetals tend to gain electrons.

Comparatively, a covalent bond is formed by the sharing of electron pairs between atoms, and these bonds are common between nonmetals. In this case, the valence electrons are not completely transferred but are instead shared in overlapping orbitals, forming a more stable arrangement of electrons that fills the outer energy levels of both atoms involved.

The presence of a double bond in the carbon chain of a phospholipid's hydrophobic tail causes the tail to become bent or 'kinked', which can increase the fluidity of the cell membrane.

When a double bond is present in the carbon chain of the hydrophobic tail of a phospholipid, the shape of the tail changes. Specifically, the tail becomes bent or 'kinked'. This happens because double bonds restrict the rotation of the carbon atoms around the bond, causing the chain to bend. The presence of such double bonds can therefore influence the properties of the phospholipid and the cell membrane in which it is a part. For example, it can increase the fluidity of the membrane, since the bent tails do not pack together as tightly as straight tails do.

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The trait that would most likely lead scientists to investigate folk remedies of tribes living in rainforest for new medicine is openness. Option 1 is correct.

This trait encompasses curiosity, originality, intellectualism, creativity, and a willingness to embrace new ideas. It is the capacity for openness that prompts scientists to explore indigenous knowledge and integrate it into scientific inquiry.

Traditional practices, such as those employed by Northwestern North American Indigenous peoples who used seawrack on burns and broadleaved plantain on insect bites, may stem from both trial and error and an empirical understanding of natural resources. Openness allows for the consideration of these methods as part of 'real science,' emphasizing their testable and evidence-based nature.

People with high levels of openness thrive in flexible situations and are motivated to learn new things, which aids in the acceptance of and adaptation to novel environments. This characteristic is essential for scientists who are delving into folk remedies and evaluating them under the rigorous conditions of scientific research.

Hence, 1. is the correct option.

The complete question is:

Which trait would most likely lead scientists to investigate folk remedies of tribes living in rain forest for new medicine? 1. openness 2. narrow-minded 3. creativity 4. skepticism

The average density of peat moss comes out to be 0.000013 g/cm3 and that of top soil is 0.002522 g/cm3, making the peat moss 'lighter' in comparison. Seven bags of peat moss are needed to cover a 10ft by 20ft area to a depth of 20 in.

First, we need to convert everything into uniform units. In this case, that would be grams and cubic centimeters.
We know that 1 lb = 453.592 g and 1 in.3 = 16.387 cm3, and 1 gal = 3785.41 cm3. Hence,
40 lb = 18143.68 g
and the volume of peat moss = 14 * 20 * 30 in.3 = 84,000 in.3 = 1,376,522.8 cm3
Similarly, volume of topsoil = 1.9 gal = 7192.279 cm3.
So, the average density of peat moss = weight / volume = 18143.68 g / 1,376,522.8 cm3 = 0.000013 g/cm3 and
the average density of topsoil = 18143.68 g / 7192.279 cm3 = 0.002522 g/cm3.

As density is mass per unit volume, the substance with a higher density is 'heavier' for the same volume. Here, the topsoil has a higher density than peat moss; hence it's correct to say that peat moss is 'lighter' than topsoil.

For part B, we need to find out how many bags are needed to cover an area of 10*20 ft.2 to a depth of 20 in. The volume needed = length*width*depth = 10 * 20 * 20/12 ft.3 = 333.33 ft3 = 9445044.416 cm3. Therefore, the number of bags = volume needed / volume of one bag = 9445044.416 cm3 / 1,376,522.8 cm3 = 6.86. As we can't buy a fraction of a bag, we round up to 7 bags.

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Answer : Option A) Chromium

Option D) Calcium

Option E) Osmium

Explanation : The elements likely conduct electricity well are chromium, calcium and osmium. As these are metals and are observed to be good conductors of heat and electricity. They have extra electrons to donate and hence flow of electrons cause them to be a good conductor of electricity. Rest iodine is a non-metals which is not good conductors of electricity. Carbon is not itself a good conductor but one of its allotrope which is graphite is a good conductor of electricity.

Sodium chloride (table salt) dissolved in water conducts electricity due to the dissociation of the salt into mobile sodium and chloride ions, which can carry electrical charges and complete an electrical circuit.

When table salt (sodium chloride, NaCl) is dissolved in water, it creates a solution that can conduct electricity. This is because salt is an ionic compound that dissociates into sodium ions (Na+) and chloride ions (Cl-) in water. These ions are capable of moving freely in the water, carrying electrical charges with them.

In contrast to solid sodium chloride, where ions are locked in place within a crystal lattice, dissolving salt into water breaks apart this lattice structure, allowing ions to move. As these charged particles flow towards oppositely charged electrodes, they complete an electrical circuit, permitting the flow of electricity.

Electrolytes like sodium and chloride are crucial for bodily functions and must be replenished when lost through activities like sweating. These are substances that when dissolved in water, their dissociated ions make the solution electrically conductive.

According to the balanced equation, 1 mole of methane reacts with 2 moles of oxygen to produce 2 moles of water. We can calculate the mass of water formed by using the molar masses of the compounds involved.

According to the balanced equation: CH4 + 2O2 → CO2 + 2H2O

We can see that 1 mole of methane reacts with 2 moles of oxygen to produce 2 moles of water. Using the molar masses of the compounds, we can calculate the mass of water formed.

The molar mass of water (H2O) is 18.016 g/mol. Therefore, the mass of 2 moles of water is (2 * 18.016) g/mol = 36.032 g/mol.

So, if 3.2 g of methane reacts with 12.8 g of oxygen to produce 8.8 g of carbon dioxide, the mass of water formed would be 36.032 g/mol - (8.8 g/mol + 44.01 g/mol) = 36.032 g/mol - 52.81 g/mol = -16.778 g/mol.

1) the basic unit of mass (SI unit) is Kg

2) the amount of matter in an object is known as density, infact the amount of matter in a unit volume is density

3) We can measure the mass with a balance

Burette: for volume

rule : for length

graduated cylinder : for volume

4) Weight is measure of force of gravity on a matter

5) the density of water = 1 g / mL at 4 C

so mass of 1 mL of water will be equal to 1 gram

Answer:

1.4×10−1 Pa

Explanation:

An atom of magnesium-26 has 12 protons and 14 neutrons. The number of protons is determined by the atomic number of magnesium (12). The number of neutrons is calculated by subtracting the atomic number from the mass number (26 - 12 = 14).

For an atom of magnesium-26 (26Mg), you need to understand its atomic structure. The atomic number of magnesium is 12, which states that a magnesium atom always contains 12 protons in its nucleus. This number defines the identity of an element and is always constant.

Magnesium-26 refers to an isotope of magnesium, where 26 represents the mass number. The mass number is the addition of the protons (p) and the neutrons (n) in an atom. In the case of magnesium-26, we already know there are 12 protons. Subtract the atomic number (number of protons) from the mass number to get the number of neutrons. That is, 26 - 12 = 14 neutrons.

So, an atom of magnesium-26 (26Mg) has 12 protons and 14 neutrons.

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Final answer:

The open spaces in ice's crystal structure contribute to its lower density compared to liquid water, allowing ice to float and providing insulation for aquatic life. Water's polarity makes it an excellent solvent for many substances, supporting life by enabling the distribution of vital nutrients and facilitating biochemical processes.

Explanation:

The open spaces in water's crystal structure make it possible for a variety of environmental and biological processes. Ice is less dense than liquid water due to its open, cage-like structure caused by hydrogen bonding. This unique property allows ice to float, creating an insulating layer on bodies of water that protects aquatic life during cold temperatures. Additionally, because water is a polar molecule, it is an excellent solvent. For instance, when sodium chloride (table salt) is placed in water, the water molecules interact with the ions in the crystal lattice and dissolve into the water, creating spheres of hydration around them.

This ability of water to serve as a solvent is crucial for life on Earth. Substances can easily disperse in water due to its molecular structure, providing essential nutrients for organisms and allowing for critical biochemical processes to occur in living organisms.

Furthermore, water's properties such as surface tension and the ability to undergo osmosis are vital for many forms of life, playing key roles at the cellular level and within ecosystems as a whole.

1 liter of 0.1 M sucrose solution means that there is 34.2 g of sucrose dissolved in water to make a 1 liter solution. This also means that there are 6.022 × 10²² molecules of sucrose in this solution.  

Molarity is a unit of concentration which describes the number of moles of solute dissolved per liter of a solution. It is calculated using the equation below:

[tex]molarity = \frac{moles \ of \ solute}{volume \ of \ solution}[/tex]

Molarity is expressed with the unit mol/L or M (read as “molar”).  It is a very useful unit of concentration because many quantitative information about the solution can be obtained from this value.

Mass of Solute from Molarity

From the molarity of a solution, the equivalent mass of the solute used to prepare the solution may be obtained with the use of the formula mass (or molecular mass) through the equation:

[tex]molarity = \frac{\frac{mass\ of \ solute}{formula \ mass}}{volume \ of \ solution}\\\\mass \ of \ solute \ = molarity \times \ volume \ of \ solution \times formula \ mass[/tex]

Number of Representative Particles from Molarity

Moreover, the number of molecules of solute present in the solution may also be obtained using the molarity and Avogadro's number.

[tex]molarity = \frac{moles \ of \ solute}{volume \ of \ solution}\\\\no. \ of \ representative \ particles \ = molarity \times volume \times 6.022 \times 10^{23} \ representative \ particles[/tex]

For this problem, the mass of the solute dissolved in the solution and the number of sucrose molecules may be obtained from the molarity of the solution.

Mass of Sucrose

[tex]mass \ of \ sucrose \ = 0.1 \ \frac{mol}{L} \times 1 \ L \times \frac{342 \ g \ sucrose}{1 \ mol}\\\\\boxed {\boxed {mass \ of \ sucrose = 34.2 \ g \ sucrose}}[/tex]

Number of Sucrose Molecules

[tex]no. \ of \ sucrose \ molecules \ = 0.1 \frac{mol}{L} \times 1 \ L \times \frac{6.022 \times 10^{23} \ sucrose \ molecules}{1 \ mol}\\\\\boxed {\boxed {no. \ of \ sucrose \ molecules \ = 6.022 \times 10^{22} \ molecules}}[/tex]

Keywords: molarity, molar concentration

One litre of a freshly prepared 0.1 M sucrose solution means that 34.2 g of sucrose is dissolved in water to get final 1 L solution.

Further Explanation:

Concentration

It is a term that is used to relatedifferent components of solution with each other. A variety of concentration terms are employed to attain this. Some of the concentration terms are mentioned below.

1. Molarity (M)

2. Mole fraction (X)

3. Molality (m)

4. Parts per million (ppm)

5. Mass percent ((w/w) %)

6. Volume percent ((v/v) %)

7. Parts per billion (ppb)

Molarity is defined as moles of solute present in one litre of solution. It is represented by M and its unit is mol/L. The expression for molarity of solution is as follows:

[tex]{\text{Molarity of solution}} = \dfrac{{{\text{Moles }}\left( {{\text{mol}}} \right){\text{of solute}}}}{{{\text{Volume }}\left( {\text{L}} \right){\text{ of solution}}}}[/tex]

We are provided with 0.1 M sucrose solution. According to the definition of molarity, this indicates that 0.1 moles of sucrose are dissolved in 1 L of the solution.  

The formula to calculate the moles of sucrose is as follows:

[tex]{\text{Moles of sucrose}} = \dfrac{{{\text{Mass of sucrose}}}}{{{\text{Molar mass of sucrose}}}}[/tex]                                            …… (1)

Rearrange equation (1) for mass of sucrose.

[tex]{\text{Mass of sucrose}} = \left( {{\text{Moles of sucrose}}} \right)\left( {{\text{Molar mass of sucrose}}} \right)[/tex]                  …… (2)

Substitute 0.1 mol for moles of sucrose and 342 g/mol for molar mass of sucrose in equation (2).

[tex]\begin{aligned}{\text{Mass of sucrose}} &= \left( {{\text{0}}{\text{.1 mol}}} \right)\left( {{\text{342 g/mol}}} \right) \\&= {\text{34}}{\text{.2 g}} \\\end{aligned}[/tex]  

Therefore 34.2 g of sucrose is dissolved in water to get final 1 L solution.

Learn more:

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Concentration terms

Keywords: concentration, concentration terms, solutions, molarity, molality, sucrose, moles, mass, molar mass, 342 g/mol, 34.2 g, 0.1 M, mass of sucrose.

Answer:

Electron.

Explanation:

According to modern atomic theory, the electron position is not considered to be discrete  or fix. We say that there is probability of finding electron in particular area around the nucleus. so this we call as that atom is a diffuse cloud of electrons surrounding a small dense nucleus.

The electron density is maximum in shells.

The modern atomic theory states that the atom is a diffuse cloud of electrons surrounding a small, dense nucleus.

The correct answer is (A) electron.

Modern atomic theory states that the atom is a diffuse cloud of electrons surrounding a small, dense nucleus. The electrons are negatively charged particles that orbit the nucleus in specific energy levels or shells. This model of the atom was proposed by Niels Bohr in 1913 and is known as the Bohr model.

For example, in a hydrogen atom, there is one electron orbiting the nucleus. In oxygen, there are eight electrons arranged in two energy levels, with two in the first level and six in the second level.

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