Write correct ionic formulas for the following light emitting compounds by entering subscripts (remember that number of electrons that are given away has to be equal to the number of electrons that are accepted). if there is only one ion, then enter number 1.

The element symbol, mass number, and charge of this ion would be:

Element symbol: Sr

Mass number: 87

Charge: +2

Given :

Protons = 38

Neutrons = 49

Electrons = 36

Mass number = protons + neutrons

Mass number = 48+49 = 87

In this case, the number of protons is 38 and the number of electrons is 36, so the charge of the ion would be 38 - 36 = +2, meaning that it is a positively charged ion (cation).

Is the mass number the number of protons and neutrons?

The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number (Z).

What is the charge of an ion?

An ion is an atom or group of atoms that has an electric charge. Ions with a positive charge are called cations. Ions with a negative charge are called anions. Many normal substances exist in the body as ions.

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a- The independent variable is the concentration of the solution, b- The dependent variable is the absorbance of the solution.

c- In Excel, the concentration data can be entered in one column and the absorbance data in another column. The concentration data would be plotted on the x-axis and the absorbance data would be plotted on the y-axis. By selecting the option for linear regression b, the best-fit slope and y-intercept can be determined.

For example, if the best-fit slope is 0.2 L/mol and the y-intercept is 0.05, the equation for the best-fit line would be y = 0.2x + 0.05, where y is the absorbance and x is the concentration in mol/L. The units for the slope would be absorbance per concentration (L/mol) and the units for the y-intercept would be absorbance (L). These values represent the relationship between the concentration of the solution and its absorbance, with the slope indicating how absorbance changes with increasing concentration.

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Reaction B (2,3-dimethylheptane) will have the largest heat of combustion. This is because the larger alkyl group of the 2,3-dimethylheptane (3 methyl groups vs 2 methyl groups in the other two isomers) will require more energy to break, resulting in a higher heat of combustion.

It is also important to note that the larger alkyl group of the 2,3-dimethylheptane means that there will be more carbon-carbon (C-C) and carbon-hydrogen (C-H) bonds to break in order to oxidize the molecule. This means that more energy is required to break these bonds and therefore the heat of combustion will be higher.

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The term mole concept is used here to determine the masses of the respective compounds. The mass of sodium carbonate is 5.935 g , silver nitrate is  0 g, silver carbonate is 4.057g, sodium nitrate is 2.496 g.

One mole of a substance is defined as that quantity of it which contains as many entities as there are atoms exactly in 12 g of carbon - 12. The formula used to calculate the number of moles is:

Number of moles (n) = Given mass / Molar mass

Here the mass of sodium carbonate is 7.50 g and its molar mass (M) is 105.988 g/mol. The mass of silver nitrate is 5.00 g and its molar mass 169.87 g/mol.

'n' of Na₂CO₃ = 7.50 / 105.988 = 0.0707 mole

'n' of AgNO₃ = 5.00  / 169.87 = 0.0294 mole

The equation for the given reaction is:

Na₂CO₃ + 2AgNO₃ → Ag₂CO₃↓ + 2NaNO₃

Here 1 mole Na₂CO₃ - 2 mole AgNO₃

x mole Na₂CO₃ - 0.0294 mole AgNO₃

x = 0.0147 mole

n (Na₂CO₃) = 0.0707-0.0147 = 0.056 mole

m  (Na₂CO₃)  = n × M = 0.056 × 105.988 = 5.935 g

n (AgNO₃ ) = n (NaNO₃) = 0.0294 mole

m (NaNO₃)  = n × M = 0.0294 × 84.9 = 2.496 g

n (Ag₂CO₃) = 0.0147 mole

m (Ag₂CO₃) = n × M = 0.0147 × 276 = 4.057 g

Thus the masses are:

sodium carbonate = 5.935 g, silver nitrate = 0 g, silver carbonate = 4.057g, sodium nitrate = 2.496 g.

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According to unit conversion, there are  0.00085 miligrams in 850 nanograms .

Unit conversion is defined as a multi-step process which involves multiplication or a division operation by a numerical factor.The process of unit conversion requires selection of appropriate number of significant figures and the rounding off procedure.

It involves a conversion factor which is an expression for expressing the relationship between the two units.A conversion ratio always has value which equals to one which indicates that numerator and denominator have values which are expressed in different units.

As 1 nanogram = 1×10[tex]^-6[/tex] mg , thus, 850 nanograms = 850×10[tex]^-6[/tex]= 0.00085 mg.

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Compounds are more stable than elements, so they have less energy in them. Alkali metals are very reactive and can release a lot of energy when they react with water. So K is the correct answer.

Alkali metals react violently with water to produce alkaline solutions and hydrogen gas. This reaction is exothermic (releasing a certain amount of energy) so that it can produce an explosion and even an explosion (if the amount of potassium metal is greater).

Alkali metals react with water to form bases and hydrogen gas. Reacted rather slowly; Na reacts violently with sparks; K, Rb, and Cs explode when placed in water.

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The work function of metal was  6.08 * 10⁻¹⁹  J

The maximum number of electrons ejected are 1.21 * 10¹²electrons

The work function of a metal is the minimum amount of energy required to remove an electron from an atom of the element.

The work function of metal can be written as: φ = h f - E

where:

φ represents the work function of a metal,

hf represents the photon energy,

E is the kinetic energy.

For the given metal:

Work function =  6.63 * 10⁻³⁴ * 1.40 * 10¹⁵ -   3.20 × 10⁻¹⁹

Work function = 6.08 * 10⁻¹⁹  J

The maximum number of electrons ejected: total energy/work function

The maximum number of electrons ejected = 7.36 * 10⁻⁷/6.08 * 10⁻¹⁹

The maximum number of electrons ejected = 1.21 * 10¹²electrons

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Based on the volume and the density of the iceberg, the mass of the iceberg is 197475.603 kg.

The volume of the iceberg in cm³ is determined as follows:

1 ft = 30.48 cm

1 ft³= 30.48 cm * 30.48 cm * 30.48 cm

1 ft³=  28316.847 cm³

The volume of the iceberg in cm³ = 7605 * 28316.847 cm³

The volume of the iceberg in cm³ = 215349621.4 cm³

The mass of the iceberg is then determined as follows:

Mass = density * volume

The mass of the iceberg = 215349621.4 cm³ * 0.917 g/m³

The mass of the iceberg = 197475602.9 g 197475.603 kg

The mass of the iceberg = 197475.603 kg

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A. temperature will increase because reaction is exothermic.

B. Average kinetic energy will increase.

C. Average speed will increase.

D. The dissolution reaction is exothermic.

Dissolution reaction is defined as the reaction where a single reactant breaks down into it's ions making an aqueous solution. If 15.0 grams of calcium chloride, CaCl2, is dissolved into 100.0 mL of water at 22.5°C, the final temperature of the solution was 32.2°C then the dissolution of CaCl2 in water is an example of exothermic reaction because heat is evolved during the process hence there is an increase in temperature is observed.  An exothermic reaction is defined as a chemical reaction in which less energy is needed to break bonds in the reactants than is released when new bonds form in the products.

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The proposed mechanism indicates that the overall reaction is a two-step process. In the first step, H2 reacts with ICl to form HCl and I2. In the second step, HCl and HI react to form H2 and ICl.

Therefore, the rate law for the overall reaction should be expressed as:

Rate= k[H2][HI][ICl]2  where k is the rate constant of the reaction and [H2], [HI], and [ICl] represent the concentrations of the reactants. The rate law indicates that the rate of the overall reaction is directly proportional to the concentration of the three reactants and is proportional to the square of the concentration of ICl. This is because, in the second step, two molecules of ICl are consumed to form H2 and HI.

Therefore, the rate law for the overall reaction is Rate= k[H2][HI][ICl]2, which is consistent with the proposed mechanism.

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when we heating a solution to boiling on a hot plate, start by starting and stabilizing the stir function then, turn the heat to a medium heat to start. If necessary, turn up the heat setting after waiting about a ten minutes without seeing the boiling.

A chemical reaction can be defined as a chemical process which typically involves the transformation or the rearrangement of the atomic, ionic or molecular structure of an element through the breakdown and the formation of chemical bonds to produce a new compound or substance.

Some of the laboratory apparatus (equipment) which are used for conducting a chemical reaction are conical flask,  beaker, Bunsen burner, crucible, round bottom flask etc.

When heating a solution to boiling on a hot plate, start by starting and to stabilizing the stir function. Then, turn up the heat to a medium heat to start it.

The safety precautions which be taken when heating a solution to boiling on a hot plate: A proper inspection of the round bottom flask for cracks, irregularities or any kind of imperfection.

Be ensure you avoid heating the flask while it is closed.

When we suspending the flask on a hot plate, you should ensure that you use a clamp for the stability.

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First, find the molecular weight of Mg(NO3)2.

The molecular weight of Mg is 24.3 g/mol and the molecular weight of NO3 (nitrate ion) is 62 g/mol.

So, the molecular weight of Mg(NO3)2 is 24.3 + (2 x 62) = 150 g/mol.

Next, we can find the number of moles in 120 g of Mg(NO3)2:

120 g / 150 g/mol = 0.8 mol

So, there are 0.8 moles of Mg(NO3)2 in 120 g.

The mass of a mole of a material is its molecular weight. Typically, grams per mole are used as the unit of measurement. In this video, we demonstrate how to determine a substance's molecular weight using the periodic table's listed atomic weights. On a different page, we perform a conversion between the macroscopic scale (represented by grams of a substance) and the microscopic scale using the molecular weight (number of molecules of that substance). The molecular weight of a material is the weight, in atomic mass units, of each atom in a specific formula. One atomic mass unit is equal to one-twelfth of the weight of carbon-12. The most accurate sign is u, while the previous one was amu (a lowercase letter u).

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In nuclear magnetic resonance (NMR) spectroscopy, the chemical shift is the resonant frequency of an atomic nucleus relative to a trendy in a magnetic field.

Often the placement and range of chemical shifts are diagnostic of the shape of a molecule. The chemical shift in absolute phrases is described via way of means of the frequency of the resonance expressed close to a trendy compound that is described to be at zero ppm. The scale is made greater workable via way of means of expressing it in elements in keeping with million (ppm) and is indepedent of the spectrometer frequency.

1)  electronegativity of atoms increases chemical shift value also increases.

2)  number of electronegative atoms increases chemical shift value is also more

3) CH4 has no Cl atoms . so it has least chemical shift

4) CHCl3 has 3  higher electronegative atoms . so it has higher chemical shift.

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The rate law of the reaction can be obtained from the concentration of the reactants.

The rate law is an equation that describes the relationship between the rate of a chemical reaction and the concentrations of its reactants. It typically takes the form of rate = k[A]^m[B]^n, where k is the rate constant, [A] and [B] are the concentrations of the reactants, and m and n are the reaction orders with respect to each reactant.

The rate law can be determined experimentally by measuring the rate of the reaction at different concentrations of the reactants.

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0.048moles are in 2.91 x 10²² atoms of He. Helium (He) is a chemical element and inert gas in Periodic Group 18 (noble gases).

Helium is a chemical element and inert gas in Periodic Group 18 (noble gases). Helium, the second smallest atom is a colorless, odorless, but tasteless gas that solidifies at 268.9 °C (452 °F).

Helium has lower boiling as well as freezing points than any other known material. Helium is the sole element that is not solidified by adequate cooling at normal pressure; it must be consolidated at a pressure of 25 earth's atmosphere at such a temperature of about one K

mole = given number of atoms/  6.022×10²³

        = 2.91   ×10²² /  6.022×10²³

       = 0.048moles

Therefore, 0.048moles are in 2.91 x 10²² atoms of He.

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In an ecosystem, all the given options are the processes that can be performed by bacteria.

Ecosystem is defined as a system which consists of all living organisms and the physical components with which the living beings interact. The abiotic and biotic components are linked to each other through nutrient cycles and flow of energy.

Energy enters the system through the process of photosynthesis .Animals play an important role in transfer of energy as they feed on each other.As a result of this transfer of matter and energy takes place through the system .

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There are  18 electrons in total for the compound HCl. The compound contains 18 protons also. The total number of neutrons is 18 as well.

Hydrogen chloride is a covalent compound formed by the sharing of electrons between hydrogen atom and Cl atom. Hydrogen is 1st element in periodic table and Cl is the 17th element.

Hydrogen contains only one electron and chlorine contain 17 electrons. Among the 17 electrons 7 are valence electrons in Cl. The number of protons in them is equal to the number of electrons.

H has no neutrons and Cl have 18 neutrons. The total number of electrons is then 1+ 17 = 18 this jus the number of protons also. Hence the compound HCl contains 18 of electrons, protons and neutrons as well.

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The absorbance of a solution containing C can be calculated using the Beer-Lambert Law, which states that absorbance (A) is equal to the product of the molar absorptivity coefficient (ε), the pathlength (l) of the light through the cuvette, and the concentration (c) of the solution.

Thus, given that the wavelength and pathlength are known, the concentration of the solution can be calculated using the equation A = εlC.

The Beer-Lambert Law is an important equation used in spectroscopy to measure the concentration of a solution based on its absorbance at a certain wavelength. The equation is based on the fact that the amount of light absorbed by a solution is proportional to the concentration of the solution and the pathlength of the light through the sample.

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Option B After recrystallization, the salicylic acid was not completely dried. Reweigh it after it has dried would be a possible explanation for the problem

To address the issue, the student could repeat the recrystallization process with proper care and attention to detail, making sure to measure the mass of the product accurately and to dry the product completely before weighing it.

They could also consider using a different recrystallization solvent or a different technique to purify the product. However, without more information about the specific circumstances, it's difficult to say for sure what the best solution would be.

An alkyl ether is an organic compound that contains an oxygen atom bonded to two carbon atoms, one of which is bonded to an alkyl group. Alkyl groups are chains of carbon atoms that are bonded together and may contain one or more carbon atoms.

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The highly reactive species that is readily dissociable is carbonic acid (H2CO3).

Why does carbonic acid react so quickly?

The acid carbonic acid is not thought to be very reactive. It actually dissociates only partially in solution because it is a weak acid. This indicates that, in a given solution, only a small portion of the carbonic acid molecules will split into hydrogen ions (H+) and bicarbonate ions (HCO3-).

The molecular structure of carbonic acid is what causes its weak acidic behavior. A carbon atom is bound to two oxygen atoms, one hydrogen atom, and two other atoms to form the compound known as carbonic acid, which is not a strong enough acid to completely dissociate in water. Due to this, it is a less reactive and dangerous acid than other ones.

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A molecular dipole moment occurs when a molecule has a positive end and a negative end, resulting in an electrically asymmetrical distribution of charge. The direction of the dipole moment is defined as pointing from the negative end to the positive end.

In general, a compound will possess a molecular dipole moment if the electronegativity values of the atoms in the molecule are different, leading to an uneven distribution of charge.

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If your spectrophotometer can measure an absorbance up to 1.5 accurately, the maximum concentration of pNA that you can measure without diluting is 310 ug/mL.

A spectrophotometer counts photons to estimate the intensity of light spectra absorbed and transmitted by a sample. This gives information about the concentration of a compound in the sample.

This is determined by the wavelength at which the measurements are taken. The absorbance at 340 nm is commonly used for NADH because it is the best and cleanest peak in the absorbance curve. An absorbance of 1.5 equals 310 ug/mL.

Thus, the maximum concentration of pNA that you can measure without diluting is 310 ug/mL.

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The molecular formula of sodium Ferrocyanide ​is Na4Fe(CN)6

What is the formula and Valency of ferrocyanide?

The ion [Fe(CN)6]4 is called ferrocyanide. Yellow solutions can be made with the coordination complex's salts. The potassium ferrocyanide salt, with the chemical formula K4Fe(CN)6, is the form in which it is typically sold. A low-spin iron(II) centre in an octahedral ligand environment characterises the diamagnetic species [Fe(CN)6]4.

What is sodium ferrocyanide used for?

The main use of ferrocyanide, an odourless, yellow solid that mixes with water, is as an anti-caking agent. This is how it is frequently added to food-grade salt to stop lumping and ensure smooth dispensing through a salt shaker.

How do you make sodium ferrocyanide?

By treating calcium ferrocyanide with sodium carbonate or sodium chloride or by boiling spent iron oxide from coal gas purifiers with lime and extracting the soluble calcium ferrocyanide therefrom, sodium ferrocyanide is typically made. It can also be made from spent iron oxide from other sources, such as spent iron oxide from coal gas purifiers.

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The chemical reaction in which ammonium sulfate and potassium hydroxide are mixed together is called double displacement (Option D)

Double displacement is a type of chemical reaction where two reactants exchange parts to form two new products. For example, when an acid and a base are combined, they produce salt and water. This reaction is known as double displacement because the ions from both reactants have exchanged places. Double displacement reactions typically involve the exchange of ions between aqueous solutions, but can also occur with solid reactants.

The chemical reaction in which ammonium sulfate and potassium hydroxide are mixed together is a double displacement reaction. In this type of reaction, the positive and negative ions of two ionic compounds switch places to form two new ionic compounds.

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The amount of heat required to raise the temperature of the system through 1°C is defined as the heat capacity of the system. The time in minutes to heat the water in the hot tub from 62 °F to 105 °F is 28.9.

The quantity of heat required to raise the temperature of one gram of the substance through 1°C is known as the specific heat capacity. It is usually denoted by c.

The equation connecting the specific heat capacity with the heat is given as:

q = mc (T₂ - T₁) = mc Δ T

1 gallons = 3.785 L

450 gallons = 450 × 3.785 = 1703.25 L

Density of water is 1 g/cm³

Then the mass of water is, m = Density × Volume

m = 1703.25 L × 1000 mL/ 1L × 1.0 g / 1mL × 1kg / 1000g

m = 1703 .25 kg

The temperature in °F can be converted into °C as:

T°C = T°F - 32 / 1.8

T₁ = 62 -32 / 1.8 = 17°C

T₂ = 105 - 32/ 1.8 = 41°C

Δ T = T₂ - T₁  = 41 - 17 = 24°C

q = 1703.25 kg × 4.184 kJ/kg K × 24°C

q = 171033.552 kJ

Here power in watt (W) = 5900 kJ/min

Then time, t = q/W = 171033.552 kJ/ 5900 kJ/ min

t = 28.9 min

Thus the time is 28.9 min.

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The compound that has the greatest number of constitutional isomers is octane (C₈H₁₈).

Constitutional isomers are different compounds with the same molecular formula, but with different arrangements of atoms in the molecule.

Molecules with fewer carbon atoms have fewer opportunities for different arrangements, resulting in fewer constitutional isomers.

Hexane, with molecular formula C₆H₁₄, has a total of 5 constitutional isomers.

Butane, with molecular formula C₄H₁₀, has 2 constitutional isomers.

Propane, with molecular formula C₃H₈, has only 1 constitutional isomer.

Octane, with molecular formula C₈H₁₈, has 9 constitutional isomers.

Hence, octane, having 9 constitutional isomers, is the compound with the greatest number of constitutional isomers.

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The number of moles of solute in 122.4 L of 0.990 M sodium cyanide is 119.082 moles. After rounding to four significant figures, the answer is 119.1 moles.

The number of moles of solute in 122.4 L of 0.990 M sodium cyanide is 119.082 moles. This can be determined by using the equation:

Where Molarity is 0.99 M and Volume is 122.4 L.

The molar mass of sodium cyanide (NaCN) is 49.01 g/mol [3], which means that 1 mole of NaCN contains 49.01 grams of the compound. This is important to know when calculating the mass of a given number of moles, as the two are directly related.

Rounding to four significant figures, the answer is 119.1 moles of sodium cyanide in 122.4 L of 0.990 M solution.

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The new pressure of the particles of heavy species of gas is 36 atm.

The correct option is B

The new pressure of the particles of heavy species of gas is determined  using the ideal gas equation as follows:

PV = nRT

where;

T is the temperature

Assuming the temperature, volume, and molar gas constant all remain unchanged, the new equation will be:

P = n

When n = 100, P = 12 atm

Ratio of n and P = 100/12

When, n = 300, P = 300 * 12/100

Pressure = 36 atm

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