7. Which of the following is a molecule?????
(A) K (C) Na
(B) Ne (D) HI ......​

Answer:

?

Explanation:

did you mean kilograms?

The Vostok ice core curve shows CO2 concentrations over the last 800,000 years.

The Vostok ice core, drilled in Antarctica at the Vostok Station, has provided valuable data on past climate conditions. By analyzing the ice layers, scientists can determine various parameters, including CO2 concentrations. The ice core data has allowed the reconstruction of CO2 levels in the atmosphere dating back hundreds of thousands of years, providing insights into long-term climate trends and the relationship between CO2 and global temperatures.

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Typically, nitrogen atoms are composed of electrons, protons, and neutrons. an isotope of nitrogen could have more number of neutrons than usual nitrogen atom.

What is proton ?

Protons include the H+ ion or the hydrogen atom's nucleus. Regardless of the isotope, each hydrogen atom has one proton, each helium atom has two, each lithium atom has three, and so on.

What is electron ?

It is possible for an electron to be free or linked to an atom. An electron is a negatively charged subatomic particle (not bound). There are three main types of particles in an atom: protons, neutrons, and an electron that is bonded to an atom. The nucleus of an atom is composed of protons, neutrons, and electrons.

Therefore, nitrogen atoms are composed of electrons, protons, and neutrons. an isotope of nitrogen could have more number of neutrons than usual nitrogen atom.

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Answer:

Nb 1= mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm

2.35 x 10²⁰ atoms are present in a 27.2 mg sample of Gallium.

The total atomic mass of all the atoms that make up a molecule is calculated using a scale where the atomic masses of hydrogen, carbon, nitrogen, and oxygen are 1, 12, 14, and 16, respectively. For instance, the molecular mass of water, which consists of two hydrogen atoms and one oxygen atom, is 18 (2 + 16).

moles of Gallium = mass of sample / molar mass of Gallium

moles of Gallium = 27.2 mg / 69.72 g/mol

moles of Gallium = 0.0003906 mol

The number of atoms can be determined using Avogadro's number:

number of atoms = moles of Ga x Avogadro's number

number of atoms = 0.0003906 mol x 6.022 x 10²³ atoms/mol

number of atoms = 2.35 x 10²⁰ atoms

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Recovery = (Weight of product recovered ÷ Theoretical yield) × 100% Recovery = (0.251 g ÷ 0.27594 g) × 100% Recovery = 91.08%Therefore, the % recovery of the reaction between 2,3-dimethyl-1,3-butadiene and maleic anhydride to form cyclic anhydride was 91.08%.

Diels-Alder Reaction   Diels-Alder reaction is a chemical process that joins a conjugated diene with a dienophile (a compound containing a double bond) to form a six-membered ring called a cyclohexene ring. It is a chemical reaction that can be used to make new carbon–carbon bonds. The reaction was discovered by two German scientists, Otto Diels and Kurt Alder, in 1928.In the Diels-Alder reaction between 2,3-dimethyl-1,3-butadiene and maleic anhydride to form cyclic anhydride, the % recovery was calculated using the following data:Weight of maleic anhydride used: 185 mg = 0.185 gVolume of diene used: 0.215 mLWeight of cyclic anhydride crystals recovered: 0.251 g% Recovery:We can calculate the percent recovery using the following formula:% Recovery = (Weight of product recovered ÷ Theoretical yield) × 100The theoretical yield of the product can be calculated from the balanced chemical equation as follows:2,3-dimethyl-1,3-butadiene + Maleic Anhydride → Cyclohexene-1,2-dicarboxylic AnhydrideThe molar mass of 2,3-dimethyl-1,3-butadiene is 68 g/mol. The molar mass of Maleic Anhydride is 98 g/mol. The molar mass of Cyclohexene-1,2-dicarboxylic Anhydride is 146 g/mol.Using these values, we can calculate the number of moles of each reactant: moles of diene used = (0.215 mL)(0.788 g/mL)/(68 g/mol) = 0.00248 mol moles of maleic anhydride used = 0.185 g/98 g/mol = 0.00189 mol The theoretical yield of cyclohexene-1,2-dicarboxylic anhydride = 0.00189 mol × 1 mol/1 mol = 0.00189 molThe theoretical yield of cyclohexene-1,2-dicarboxylic anhydride = 0.00189 mol × 146 g/mol = 0.27594 gNow, we can substitute these values into the percent recovery equation:% Recovery = (Weight of product recovered ÷ Theoretical yield) × 100% Recovery = (0.251 g ÷ 0.27594 g) × 100% Recovery = 91.08%Therefore, the % recovery of the reaction between 2,3-dimethyl-1,3-butadiene and maleic anhydride to form cyclic anhydride was 91.08%.

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There are two main types of isomers:

a) Geometric isomers (also known as cis-trans isomers): Geometric isomers have the same atom-to-atom connections, but differ in the orientation of functional groups around a double bond or a ring structure. For example, cis-2-butene and trans-2-butene are geometric isomers with the same molecular formula and the same atom-to-atom connections, but different spatial arrangements.

b) Optical isomers (also known as enantiomers): Optical isomers are mirror images of each other and cannot be superimposed on each other. They have the same molecular formula, the same atom-to-atom connections, but differ in the spatial arrangement of atoms or functional groups around a chiral center. Optical isomers may have different physical and chemical properties and interact differently with other molecules. An example of optical isomers is L- and D-glucose.

The mass of iron produced when 11.0 g of aluminum reacts with 30.0 g of iron (III) oxide is approximately 10.48 grams.

To determine the mass of iron produced when 11.0 g of aluminum reacts with 30.0 g of iron (III) oxide, we need to balance the chemical equation and perform stoichiometric calculations.

The balanced chemical equation for the reaction between aluminum and iron (III) oxide can be written as follows:

2 Al + Fe₂O₃ → 2 Fe + Al₂O₃

From the balanced equation, we can see that 2 moles of aluminum react with 1 mole of iron (III) oxide to produce 2 moles of iron and 1 mole of aluminum oxide.

Convert the given masses of aluminum and iron (III) oxide into moles.

Using the molar mass of aluminum (26.98 g/mol) and iron (III) oxide (159.69 g/mol), we can calculate the number of moles for each substance.

Number of moles of aluminum = mass of aluminum / molar mass of aluminum

= 11.0 g / 26.98 g/mol

= 0.408 moles

Number of moles of iron (III) oxide = mass of iron (III) oxide / molar mass of iron (III) oxide

= 30.0 g / 159.69 g/mol

= 0.188 moles

Determine the limiting reactant.

To determine the limiting reactant, we compare the stoichiometric ratio of aluminum to iron (III) oxide. From the balanced equation, we see that 2 moles of aluminum react with 1 mole of iron (III) oxide.

Given that we have 0.408 moles of aluminum and 0.188 moles of iron (III) oxide, we can calculate the moles of iron that can be produced from each reactant.

Moles of iron from aluminum = 2 * 0.408 moles = 0.816 moles

Moles of iron from iron (III) oxide = 0.188 moles

Since the moles of iron from aluminum (0.816 moles) is greater than the moles of iron from iron (III) oxide (0.188 moles), we can conclude that iron (III) oxide is the limiting reactant.

Calculate the mass of iron produced.

To calculate the mass of iron produced, we use the molar mass of iron (55.85 g/mol) and the number of moles of iron from the limiting reactant.

Mass of iron = moles of iron from iron (III) oxide * molar mass of iron

= 0.188 moles * 55.85 g/mol

= 10.48 g

Therefore, the mass of iron produced when 11.0 g of aluminum reacts with 30.0 g of iron (III) oxide is approximately 10.48 grams.

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Answer:

E) 9.0

Explanation:

pH = -log [1×10^-9] = 9

Answer:

Radiation is responsible for most of the heat transferred into the room. Heat transfer also occurs through conduction into the room, but at a much slower rate. Heat transfer by convection also occurs through cold air entering the room around windows and hot air leaving the room by rising up the chimney.

When a fluid, such as air or a liquid, is heated and then travels away from the source, it carries the thermal energy along. This type of heat transfer is called convection. The fluid above a hot surface expands, becomes less dense, and rises. ... A space heater is a classic convection example.

The weight of each stopper can vary based on the material, size, and manufacturing process used, so it is not possible to determine the number of rubber stoppers needed without more information.

Weight is a measure of the force of gravity on an object and is typically measured in units of Newtons (N), pounds (lb), or kilograms (kg).

Average weight, on the other hand, refers to the sum of the weights of a group of objects divided by the number of objects in the group. It provides an estimate of the typical or central value of the weights in the group. The units of average weight are the same as the units used to measure weight.

The number of rubber stoppers needed to contain the same number of stoppers as there are corks in 1.0 kg of corks would depend on the average weight of each type of stopper.

The weight of each stopper can vary based on the material, size, and manufacturing process used, so it is not possible to determine the number of rubber stoppers needed without more information.

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Based on the mole ratio of the reaction and the volume of the reactants used;

The amount of sodium hydroxide that reacted with hydrochloric acid is calculated from the mole ratio of the reaction between hydrochloric acid and sodium hydroxide.

The equation of the reaction is given as follows:

HCl (aq) + NaOH (aq) ---> NaCl + H₂O

The mole ratio of HCl and NaOH is 1 : 1

Moles of HCl in 24.40 cm³ of 0.120 mol dm of hydrochloric acid solution will be determined as follows:

Moles of HCl = 0.120 * 24.40 / 1000

Moles of HCl = 0.002928 moles

Thus moles of NaOH reacted = 0.002928 moles

The amount of sodium hydroxide unreacted in 200 cm³ solution is determined as follows:

Moles of sodium hydroxide unreacted in 25 cm³ solution = 0.002928 moles

Moles of sodium hydroxide unreacted in 200 cm³ solution = 0.002928 moles * 250 / 25

Moles of sodium hydroxide unreacted in 200 cm³ solution = 0.0234 moles.

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Answer:

i dk how ur school works, but you'll most likely have to take that science again to get the credits u need to graduate

Explanation:

The electronegativity of an atom determines how strongly it attracts electrons in a bond. When atoms with different electronegativities are bonded together, the shared electrons are not equally shared, leading to the formation of a bond dipole.

The direction of the bond dipole is from the less electronegative atom towards the more electronegative atom.

In this series, the electronegativity of the central atom increases from B to C to N, while the electronegativity of the bonded hydrogen atom remains relatively constant. Therefore, the bond dipoles are expected to increase in magnitude from a) BâH > CâH > NâH, since the difference in electronegativity between the central atom and the hydrogen atom becomes larger as we move from N to C to B. The direction of the bond dipoles is from the hydrogen atom towards the central atom.

Therefore, the correct answer is a) BâH > CâH > NâH.

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Answer:

which one is isn't the one that is wrong

Explanation:

bang bang chocho train

Answer:

41.45 mL

Explanation:

Applying the general gas equation,

PV/T = P'V'/T'............... Equation 1

Where P = Initial pressure of hydrogen, V = Initial volume of hydrogen, T= Initial Temperature of hydrogen, P' = Final pressure of hydrogen, V' = Final Volume of Hydrogen, T' = Final Temperature.

make V' the subject of the equation

V' = PVT'/TP'................ Equation 2

Given: P = 718 torr = (718×133.322) N/m² = 95725.196 N/m², V = 47.9 mL = 0.0479 dm³, T = 26 °C = (26+273) = 299 K, T' = 273 K, P' = 101000 N/m²

Substitute these values into equation 2

V' = ( 95725.196×0.0479×273)/(299×101000)

V' = 0.04145 dm³

V' = 41.45 mL

11.1 grams of calcium chloride should be dissolved in 500. 0mL of water to make a 0. 20 M solution of calcium chloride.

Molarity of a solution is defined as the number of moles of solute present in 1 litre of a solution.  1 mole of any substance is equal to 6.022× 10²³ atoms, ions or molecules present in it.

0.2M means 0.2mol CaCl₂/1L solution.

This question didn't give us a density of the solution so needs an assumption that the solution has equal volume to water.

x mol/0.5L=0.2M

x = 0.1

0.1 mol of CaCl₂ is needed. Ca=40g/mol, Cl=35.5g/mol.

CaCl₂ 0.1mol = (40+35.5×2)×0.1=11.1g

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Answer:

Products are copper and magnesium sulphate

Explanation:

\({ \bf{A+B→C+D}}\)

A and B are reactants

C and D are products

Approximately x% of the acid is dissociated in a 0.50 M solution of HA at 25°C.

The percent dissociation of an acid can be determined using the acid dissociation constant (Ka) and the initial concentration of the acid (HA). The mathematical expression for percent dissociation is:

Percent Dissociation = (Dissociated HA concentration / Initial HA concentration) * 100

In this case, we are given that the acid dissociation constant (Ka) for acid HA is known at 25°C, and we have a 0.50 M solution of HA. However, the value of Ka and specific acid are not provided, so we cannot calculate the exact percent dissociation.

To calculate the percent dissociation, you would need the value of Ka for the specific acid, which indicates the extent of dissociation at equilibrium. Based on this value and the initial concentration of HA, you can calculate the dissociated HA concentration and then use the mathematical expression mentioned above to determine the percent dissociation.

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Answer:

Due to warm temperature.

Explanation:

There is water present in liquid form instead of liquid nitrogen on the outer side of the can because of the temperature present in the surrounding environment. The temperature around the can is little warm which is favourable for the water but not for the liquid nitrogen. The liquid nitrogen present in liquid state when the temperature of the surrounding is too cold. if it is warm, the liquid nitrogen starts boiling and converts into gaseous state so that's why the warmer temperature is responsible for the presence of water not the liquid nitrogen.

Answer:

Its ability to lose electrons

Explanation:

The attraction from the positive nucleus to the negative electron is less. This makes it easier to remove the electron and makes the atom more reactive.

Answer:

When it's able to lose electrons when it bonds with another substance.

Answer:

0.008303 mol and 0.0997 g

Explanation:

From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.022×10²³ atoms.

This implies that 1 mole of carbon also contains 6.022×10²³ atoms.

Next, we shall determine the mole of carbon that contains 5.0×10²¹ atoms. This can be obtained as follow:

1 mole of carbon contains 6.022×10²³ atoms.

Therefore, Xmol of carbon will contain 5.0×10²¹ atoms i.e

Xmol of carbon = 5.0×10²¹ / 6.022×10²³

Xmol of carbon = 0.008303 mole

Therefore, 0.008303 mole of carbon contains 5.0×10²¹ atoms.

Finally, we shall determine the mass of carbon. This can be obtained as follow:

Mole of carbon = 0.008303 mole

Molar mass of carbon = 12.01 g/mol

Mass of Carbon =.?

Mole = mass /Molar mass

0.008303 = mass of carbon/12.01

Cross multiply

Mass of Carbon = 0.008303 x 12.01

Mass of Carbon = 0.0997 g.

The refrigerator would use 180 kilowatt-hours (kWh) of electric energy over the course of 30 days, assuming it runs for 12 hours each day.

To calculate the kilowatt-hours (kWh) of electric energy used by the refrigerator in 30 days, we need to multiply the power rating by the total running time.

Given:

Power rating of the refrigerator = 500 W

Running time per day = 12 hours

Number of days = 30

First, we need to convert the power rating from watts to kilowatts:

Power rating = 500 W / 1000 = 0.5 kW

Next, we calculate the total energy used in kilowatt-hours (kWh) over the 30-day period:

Energy used = Power rating × Running time × Number of days

Energy used = 0.5 kW × 12 hours/day × 30 days

Energy used = 180 kWh

Therefore, the refrigerator would use 180 kilowatt-hours (kWh) of electric energy over the course of 30 days, assuming it runs for 12 hours each day.

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A. Lower percent yield of product

B. Lower percent yield of product

C. Higher percent yield of product

D. Lower percent yield of product

A. Washing the product with water instead of acetone can lead to impurities remaining in the product, which can lower the percent yield.

B. Not removing all the acetone can lead to residual solvent in the product, which can lower the percent yield.

C. Rinsing the beaker with the additional ethanol can lead to more product being collected, which can increase the percent yield.

D. Dissolving the anhydrous copper (II) sulfate in more than 10 mL of water can lead to dilution of the reactants, which can lower the percent yield.

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Answer:

D

Explanation:

Radioactivity means

the emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei

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Answer:

somebody answer this please>>>!!!

Explanation:

!!!

It represents an amine group.

Based on the activity series of metals, it can be observed that Magnesium being most reactive is not dispalaced by any metal from it's solution whereas copper being the least reactive is displaced by all the metals from it's solution.

The activity series of metals is an arrangement of metals based on their reactivities, from the most reactive to the least reactive.

Based on the activity series of metals, the following will be observed:

Zinc nitrate solution + magnesium metal = Magnesium dissolves and zinc metal is obtained

Zinc nitrate solution + Copper metal = No reaction

Zinc nitrate solution + Iron metal = no reaction

Magnesium nitrate solution + Zinc metal = No reaction

Magnesium nitrate solution + copper metal = No reaction

Magnesium nitrate solution + Iron metal = No reaction

Copper nitrate solution + Zinc metal = Zinc metal dissolves and copper metal is produced

Copper nitrate solution + Magnesium metal = Magnesium dissolves and copper metal is produced

Copper nitrate solution + Iron metal = Iron metal dissolves and copper metal is produced

Iron nitrate solution + Zinc metal = Zinc metal dissolves and iron metal is obtained

Iron nitrate solution + Magnesium metal =Magnesium metal dissolves and iron metal is obtained

Iron nitrate solution + Copper metal = No reaction

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Answer:

the answer is a.10

Explanation:

in(No/N) = kt

No = 80 mg

N = 10 mg

t = 30 min

solve for k, then

k = 0.693/t1/2

Substitute k from above and solve for t1/2

10 min is correct.

Radioactive element keeps on decaying over the time. Decay of radioactive element always comes under first order kinetics. The element's half-life of decay of 80mg of a radioactive element decays to 10 mg in 30 mins is 10.04 minutes. The correct option is option A.

Half life tells about the time at which the radioactive material decays to half of its initial concentration.

Mathematically, the initial and final amount of radioactive material can be connected as

ln(No/N) = kt

No =initial amount of radioactive decay= 80 mg

N = final amount of radioactive decay=10 mg

t =time taken to decay= 30 min

K= rate constant

ln( 80 mg/10 mg) = k×30 min

0.069min⁻=k

k = 0.693/half life

half life=10.04min

Therefore the element's half-life of decay of 80mg of a radioactive element decays to 10 mg in 30 mins is 10.04 minutes. The correct option is option A.

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Answer:

7.5mL of the stock solution

Explanation:

A stock solution is a concentrated solution that is used to make another more diluted solution.

In the problem, the RFC solution is 20% (v/v). That means contains 20mL of RFC in 100mL of solution.

Yo need to prepare 50.0mL of a 3.0% (v/v), solution (3mL of RFC in 100mL of solution). That means you need:

50.0mL solution × (3mL RFC / 100mL solution) = 1.5mL of RFC. These RFC must come from the stock solution

As your stock solution contains 20mL of RFC per 100mL of solution, you will need:

1.5mL RFC × (100mL stock / 20mL RFC) =