How can the mixture of sand and naphthalene be separated?

The half-life of fluorine-21 is approximately 15.8 seconds.

The half-life of a radioactive isotope is a measure of the time it takes for half of the original amount of the isotope to decay. In the case of fluorine-21, the original sample had a mass of 80.0 milligrams. After 8.32 seconds, only 20.0 milligrams of this original sample remained unchanged. To calculate the half-life of fluorine-21, we can use the equation:

Half-life = (8.32 seconds) × (ln(80.0 mg / 20.0 mg) / ln(2))

where ln(80.0 mg / 20.0 mg) is the natural logarithm of the ratio of the initial to remaining mass, and ln(2) is the natural logarithm of 2.

Half-life = 8.32 × (2.302 / 0.693) seconds

Half-life = approximately 15.8 seconds

So, the half-life of fluorine-21 is approximately 15.8 seconds. This means that, if we started with 80.0 milligrams of fluorine-21, after 15.8 seconds, only half of that original amount (or 40.0 milligrams) would remain unchanged.

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The number of protons and neutrons in 16o will be 8 protons + 8 neutrons, 17o will be 8 protons + 9 neutrons and 18o will be 8 protons +10 neutrons.  

Isotopes are the two or more types of atoms (or nuclides is the technical term) that have the same atomic number (number of protons in their nuclei) as well as the position in the periodic table (and hence belong to the same chemical element), and that is differ in nucleon numbers (mass numbers) due to the different numbers of neutrons in their nuclei

Oxygen has three stable isotopes: 16o, 17o, and 18o. The atomic number of an element is the total number of protons in an isotope. The number of neutrons is the difference between the mass as well as the atomic number

16= 8 protons + 8 neutrons

17= 8 protons + 9 neutrons

18= 8 protons +10 neutrons

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Polyethylene differs from oil, grease, and wax in a way that polythene is a tough plastic while the wax or grease is brittle solid.

Polyethylene is a long chain of ethylene, C2H6, which are molecules attached end-to-end in generally a straight chain. Oils, greases, and wax are a mixture of multiple hydrocarbon molecules which randomly combined in more of a mixture. Because of the high molecular weight of polythene, it is a tough plastic while the wax or grease is brittle solid.

One major difference among polymers and small molecules or monomers are the characteristics which polymers exhibit. Polymers generally have higher viscosities, higher boiling points and can present improved mechanical strength over small molecules or monomers.

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The location and light reflected on the moon throughout the month changes thanks to the moon's lunar phases :

At the beginning of the lunar cycle, the Moon is located between the Sun and the Earth, and is not visible from Earth because it is not reflecting any sunlight. As the Moon moves away from the Sun, a thin crescent shape becomes visible, and it is illuminated on the right-hand side. This phase is called the Waxing Crescent.

The Moon continues to move away from the Sun, and more than half of its surface becomes illuminated. This is called the Waxing Gibbous phase. After two weeks, the Moon is located on the opposite side of the Earth from the Sun, and its entire visible surface is illuminated. This is called the Full Moon phase.

The Moon continues to move closer to the Sun, and less than half of its surface is illuminated. This is called the Waning Crescent phase.

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The Grignard reaction will fail in the presence of water as the Grignard reagent will get destroyed by reacting with acidic hydrogen atoms of water.

Hence, D. water is the correct option.

The Grignard reaction is basically an organometallic chemical reaction which involves a Grignard reagent. A Grignard reagent is the alkyl, vinyl, allyl, or aryl-magnesium halides. It is reacted with a particular carbonyl group which is  in an aldehyde or in a ketone. This reaction is crucial  for the formation of the carbon–carbon bonds.

The Grignard reagent tends to get destroyed by the reaction with acidic hydrogen atoms present in the water, phenols, alcohols, or in the carboxylic acid groups. Therefore, Grignard reaction fails in the presence of water.

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The substances are the heterogeneous mixtures are : a. II and III that is  the milk of magnesia and the crude oil.

The mixture are formed when two or the more substances are mix together without taking part in the chemical change. The heterogeneous mixture is the mixture where the components throughout the solution is not uniform. The mixture are two types :

In the heterogenous mixture the particles is distributed non uniformly and it can not be separated by the physical method.

Thus, the heterogenous mixture in the given option are the milk of the magnesia and the crude oil.

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Sunset yellow (E110) is a molecule with 11 carbon atoms and 17 hydrogen atoms.

Sunset yellow (E110) is a synthetic food dye with the chemical formula C16H10N2O7S. The number of carbon atoms in the molecule can be determined by counting the number of carbon atoms in the chemical formula. In this case, there are 16 carbon atoms in the molecule.

The number of hydrogen atoms can be estimated by using the general formula for organic compounds, which is CnH2n+2, where n is the number of carbon atoms. If we plug in n = 16 into this formula, we get C16H2(16)+2 = C16H34.

This is the theoretical number of hydrogen atoms in the molecule, but it's possible that some of these hydrogen atoms have reacted with other elements to form different chemical compounds.

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The molarity of a solution that was prepared by dissolving 82.0 g of calcium chloride in enough water to make 812 mL of solution is 0.91M.

Molarity is the concentration of a substance in solution, expressed as the number moles of solute per litre of solution

The Molarity of a solution can be calculated using the following formula:

Molarity = no of moles ÷ volume

According to this question, a solution was prepared by dissolving 82.0 g of calcium chloride in enough water to make 812 mL of solution. The molarity can be calculated as follows:

no of moles of Calcium chloride = 82.0g ÷ 110.98 g/mol = 0.74 mol

Molarity = 0.74 ÷ 0.812 = 0.91M

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Magnetic Quantum Number represents the individual orbital (orientation of the orbital) an electron occupies.

Between spin and azimuthal quantum number, the magnetic quantum figure comes in third on the list. The electron is placed in one of the numerous orbitals established by the partition of the subshells (such as s, p, d, and f). It determines the spatial direction of an orbital of a certain energy (n) and form (I).

The primary quantum number (n), the orbital angular momentum quantum number (l), the magnetic quantum number (ml), and the electron spin quantum number are the four quantum numbers that comprise an atom (ms)

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$70 won't be enough to buy 15 pizzas. Since, the total money required to feed everyone is $73.9.

4 slices of pizza for each person

The amount of pizza required for 15 person => 15 x 4 = 60

12 slices get fro 1 pizza

Hence, the number pizza required => 60/12 => 5

The cost of 5 pizzas = 5 x $14.78 = $73.9

Everyone is worried about the rising cost of living right now since it is affecting their own finances. Issues about money can also affect our well-being and mental health. It's typical to experience depression or anxiety if you have to make difficult choices concerning what you can afford.

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My claim is that infrared photography can be used to visualize temperature differences by capturing the infrared radiation emitted by objects and converting it into visible light, with warmer objects appearing brighter and cooler objects appearing darker in the final image. This is because all objects emit some level of infrared radiation, and the amount of radiation emitted increases as the temperature of the object increases. By using a specialized camera that is sensitive to infrared radiation, it is possible to capture these differences in radiation and convert them into visible light, allowing the viewer to see temperature variations in the final image.

f1 refers to the first electron shell or energy level in an element's electron configuration.

In the periodic table, elements are arranged based on the number of protons in their nucleus and the electron configuration of each element.

The electron configuration specifies the arrangement of electrons in each of the element's energy levels. The first energy level, denoted as f1, is the closest to the nucleus and can contain a maximum of 2 electrons.

This information is useful for determining the chemical and physical properties of elements, including their reactivity and bonding behavior.

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The concept of significant figures is a crucial aspect of chemistry. In chemistry, significant figures are used to convey the level of precision of a measurement.

The number of significant figures in a measurement is the number of digits that are known with certainty, plus one additional digit that is estimated. This concept is used in a variety of different types of measurements, including volume, mass, and length.

1.) a. 3 significant figures (508.0)

b. 5 significant figures (820,400.0)

c. 5 significant figures (1.0200 x 10^5 kg)

d. 6 significant figures (807,000 kg)

2.) a. 7 significant figures (0.049450)

b. 3 significant figures (0.000482 mL)

c. 7 significant figures (3.1587 x 10^-4 g)

d. 4 significant figures (0.0084 mL)

3.) 10 with 2 significant figures: 1.0 x 10^1

100 with 3 significant figures: 1.00 x 10^2

1000 with 4 significant figures: 1.000 x 10^3

By understanding the concept of significant figures, chemists are able to communicate their results accurately and effectively.

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DMSO and deuterated chloroform are the most widely solvents used in NMR spectroscopy.

DMSO is the most widely used organic solvent in the NMR analysis due to its wide range of solvent constraints as well as its simple spectrum and having high boiling point. The reaction of the organic compounds with heavy water in the presence of a suitable catalyst which is used to produce deuterium solvents.

Deuterated chloroform, also called as chloroform-d, is the organic compound having formula C₂HCl₃ or CDCl₃. Deuterated chloroform is commercially available. It is easily produced and less expensive than to the deuterated dichloromethane. It is produced by the reaction of hexachloroacetone with deuterium oxide, using pyridine as a catalyst.

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The number of electrons, protons, and neutrons does the isotope of 34/16 sulfur atom contain are 16, 16, and 18 respectively.

The atomic number is equal to the amount of protons in the atom's nucleus (Z). In a neutral atom, there are precisely as many electrons as protons. The overall number of protons and neutrons in the atom's nucleus is equal to the mass number (M) of the atom.

Atomic mass number = number of proton + number of neutron

The sulphur mass number => 34

Proton number = 16

Neutron => 34-16 => 18

The overall number of protons and neutrons in an atom's nucleus is termed as the mass number in nuclear physics.

Neutrons are neutral subatomic particles that are contained in all atomic nuclei, with the notable exception of common hydrogen. Its rest mass is 1.67492749804 1027 kg, which is somewhat greater than that of the proton but 1,838.68 times higher than that of the electron. It has no electric charge.

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The use of carbon dioxide as a blowing agent has several environmental advantages over the use of CFCs and hydrocarbons.

Carbon dioxide is a naturally occurring gas and is non-toxic, non-flammable, and non-ozone depleting. It is also more energy efficient than its alternatives, resulting in lower energy costs.

Additionally, the use of carbon dioxide as a blowing agent reduces the need for other more harmful blowing agents, helping to reduce the environmental impact of their production and use.

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Answer:

11.11%

Explanation:

The concentration of the solution can be calculated by dividing the mass of the solute (common salt) by the mass of the solvent (water) and then multiplying by 100.

The concentration of the solution is:

(50g / 450g) x 100 = 11.11%.

We would need stock solutions of 20 ml of 1 M NaCl and 50 ml of 2 M MgCl₂ to prepare 500 mL of buffer A (100 mM NaCl and 250 mM MgCl₂).

The amount of NaCl and MgCl2 needed can be calculated using the formula for buffer concentration:

C1 × V1 + C2 × V2 = C_buffer × V_buffer

where C1 and C2 are the stock concentrations of NaCl and MgCl₂, V1 and V2 are the volumes of NaCl and MgCl₂ stock solutions needed to prepare the buffer, and C_buffer and V_buffer are the final concentration and volume of the buffer.

We know the final concentration of the buffer (100 mM NaCl and 250 mM MgCl₂) and the volume of the buffer (500 mL), so we can solve for the volumes of the stock solutions needed:

V1 = (C_buffer × V_buffer - C2 × V2) / C1

V1 = (100 × 0.5 - 250 × V2) / 1000

V2 = (C_buffer × V_buffer - C1 × V1) / C2

V2 = (100 × 0.5 - 1000 × V1) / 250

V1 = (100 × 0.5 - 250 × (100 × 0.5 - 1000 × V1) / 250) / 1000

V1 = (100 × 0.5 - 250 × 100 × 0.5 / 250 + 250 × 1000 × V1 / 250) / 1000

V1 = (100 × 0.5 - 100 × 0.5 + 1000 × V1) / 1000

V1 × 1000 = 100 × 0.5 / 1000

V1 = 100 × 0.5 / 1000

V1 = 0.05 L = 50 mL

So the volume of the stock solution of 2 M MgCl₂ is 50 ml.

V2 = (100 × 0.5 - 1000 × 50 mL) / 250

V2 = (100 × 0.5 - 1000 × 0.05 L) / 250

V2 = (100 × 0.5 - 50) / 250

V2 = 0.2 L = 20 mL

So the volume of the stock solution of 1 M NaCl is 20 ml.

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From the given diagrams, all diagrams represent the nucleus of an atom.

The number of different elements represented by the diagrams is three elements.

The center of an atom's small, compact region made up of protons and neutrons are known as the atomic nucleus.

The nucleus contains the mass of an atom.

The sum of the number of neutrons and protons in the nucleus of an atom gives the atomic number of an atom.

When the nucleus of an atom contains the same number of protons but a different number of neutrons, the atoms are called isotopes.

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The density of the Helium atom is 9.5 * 10^35 g/cm^2.

Density is a measure of mass per unit of volume of a substance or object. It is calculated as the ratio of the mass of an object to its volume and is usually expressed in kilograms per cubic meter (kg/m^3) or grams per cubic centimeter (g/cm^3).

We know that the mass of the atom of the helium is 4 g and the density of the atom is  0.10 nm or 1 * 10^-12 cm.

Volume of the atom = 4/3 πr^3

= 4.2 * 10^-36 cm^3

Then we must write that;

Density = mass/volume

Density = 4 g /4.2 * 10^-36 cm^3

Density = 9.5 * 10^35 g/cm^2

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Moseley offering a different explanation than Mendeleev on the organization of elements advance science by option  B. It established atomic numbers as the basis for the periodic table

The empirical knowledge is important by option D. It helps scientists make observations.

Moseley's contribution to the organization of elements advanced science by establishing atomic numbers as the basis for the periodic table (Option B). This helped to improve the accuracy of the periodic table, making it possible to predict the properties of new elements based on their atomic number.

Therefore, Empirical knowledge is important because it provides science with facts (Option A). Empirical knowledge is based on observations and experiences, which can be tested and verified through experiments. This helps to build a solid foundation for scientific understanding, as empirical knowledge provides a basis for scientific theories and models.

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The temperature at which ethanol distill at 1 atm (760 mm hg) would be 350K.

Distillation, also known as classical distillation, is the process of separating the components or substances from a liquid mixture via selective boiling and condensation, often inside a still. Dry distillation is the process of heating solid materials to create gaseous products (which might condense into liquids or solids); this can entail chemical changes such as destructive distillation or cracking.

Distillation can result in either an essentially complete separation (resulting in nearly pure components) or a partial separation that increases the concentration of specific components; in either case, the process takes advantage of differences in the relative volatility of the mixture's components. Distillation is a unit operation of virtually universal relevance in industrial applications, although it is a physical separation process, not a chemical reaction.

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Answer:

The heat required to boil water is called the heat of vaporization, and it is the amount of energy required to change the state of a substance from a liquid to a gas at a constant temperature. The heat of vaporization for water is approximately 40.7 kJ/mol or 2257 J/gram.

To calculate the heat required to boil 50.0 grams of water, you would multiply the heat of vaporization (2257 J/g) by the number of grams of water:

Heat (J) = 2257 J/g x 50 g

Heat (J) = 112,850 J

To convert Joules to kilojoules (kJ), divide by 1000.

Heat (kJ) = 112,850 J / 1000 = 112.85 kJ

Therefore, it takes 112.85 kJ of heat to boil 50.0 grams of water.

Pentose sugars include (Glyceraldehyde) and (None of the Above).

c are a class of monosaccharides, which are simple sugars, consisting of five carbon atoms. They are crucial components of many biological processes, including the synthesis of nucleic acids (DNA and RNA) and the production of energy. Ribose, which is a component of RNA, is the most prevalent pentose sugar. Xylose, a pentose sugar that is present in many plant cell walls and is utilised as a sweetener, is a further significant pentose sugar. Pentose sugars, in contrast to hexose sugars (such as glucose and fructose), cannot be digested by humans and must be consumed through diet. They are crucial for the creation of biofuels as well since they may be fermented to create ethanol. In conclusion, pentose sugars are essential parts of numerous biological systems.

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The right answer is (d) all of these. 4-aminobutanol/h, 5-aminobutanol/h, and 6-amino-2-hexanone/h can all be used to make cyclic imines.

In the intraperitoneal mouse bioassay, the newly identified class of marine biotoxins known as cyclic imines (CIs) causes a characteristically quick death. These poisons are macrocyclic substances having imine (a double bond between carbon and nitrogen) and spiro-linked ether moieties. chemical makeup. The cyclic imine group, which is typically found as a spiroimine, and the spiroketal ring system are two highly conserved moieties that make up the overall chemical structure of cyclic imine toxins. The macrocyclic ring of cyclic imine toxins has 14 to 27 carbon atoms.

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That would indicate that we also had 4 moles of water since 2 (moles H2O/molesNa2SO4). This implies that 4 moles of water should have produced.

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Answer:

Chalk is heavier it will sink and settle down

The sum of the numbers of neutrons(present in the atomic nucleus) and electrons(present outside the atomic nucleus) in the ion 116sn3+ is 113.

Atomic number of Sn (Tin) is 50. This means that isolated Sn atom has 50 electrons. Number of electrons = number of protons in nucleus. So, isolated Sn atom has 50 protons in nucleus. According to question, we have Sn3+ ion. This ion lost 3 electrons from its valence shell. But, the 50 protons still remain in its nucleus. Now, atomic mass = number of protons + number of neutrons in atomic nucleus. Given atomic mass number is 116. Hence, 116 = 50 + number of neutrons in atomic nucleus. Thus, number of neutrons in atomic nucleus = 116 - 50 = 66. The question asked for the sum of the numbers of neutrons and electrons in the ion 116sn3+ , which is 66+ 47 = 113.

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The molar mass of unknown gas is 38.65 gm  

We know that the Ideal gas equation is

PV = n R T

at Standard temperature and pressure

P = 1 atmospheric pressure

T= 273.15 Kelvin

R  = 8.3144598

V= 14.24

number of moles =  [tex]\frac{given mass}{molar mass}[/tex]

Ar  molar  mass= 40

Ar moles = 6.3/40

Ne = 20

Ne moles = 6.3 / 20

m= unknown gas

m = 6.3 / m

We know that at STP 1 mol of any gas is 22.4 l

we can obtain the total number of moles of the mixture by dividing it by 22.4L as 14.24/22.4=  0.635

0.635 =  Ar moles  + Ne moles  +  unknown gas moles

0.635 =  0.472 +  6.3/ m

m = 38.65 gm  

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Roco being chemist preparing compounds, and ionic bonds. The answer of the questions are the given below:

1. Rocco is making bonds when he prepares the compounds.

Evidence:

2. The bonds in these compounds are ionic bonds.

Evidence:

3. Rocco may only be getting half as much magnesium compound because magnesium has a higher electronegativity than lithium, meaning that magnesium attracts electrons more strongly than lithium does. This means that the magnesium-bromine bond is stronger and therefore requires more energy to form. To increase his yield, Rocco could try to add more energy to the reaction, for example by using a higher temperature or longer reaction time.

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