Calculate the hardness of a water sample which is 35.1 ppm Mg2+ and 65.8 ppm Ca2+.

The forensic scientist best categorize this blood stain by impact. Thus option B is correct.

Forensic science is defined as the application of science to criminal and civil laws, with a focus on the criminal side during a criminal investigation as defined by the legal requirements of admissible evidence and criminal procedure.

There are various laws and principles of forensic science.

Thus, the forensic scientist best categorize this blood stain by impact. Thus option B is correct.

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The nitrogen in ammonium nitrate contains a greater percentage of nitrogen by mass

The formula for ammonium nitrate is given as NH4NO3.

Determine the molar mass of NH4NO3

Molar mass = 14 + 4(1) + 14 + 3(16)

Molar mass .= 14 + 4 + 14 + 48

Molar mass of NH4NO3 = 80g/mol

Determine the percentage of nitrogen in the compound

%N = 28/80 * 100

%N = 35%

The formula for ammonium phosphate is (NH4)3PO4

Determine the molar mass of (NH4)3PO4

Molar mass = 3(14) + 4(3) + 4(16) + 3(31)

Molar mass = 42 + 12 + 64 + 31

Molar 1ass = 149g/mol

Determine the percentage of nitrogen in ammonium phosphate:

%N = 42/149 * 100

%N = 28.18%

Hence the nitrogen in ammonium nitrate contains a greater percentage of nitrogen by mass

Answer:

the water becomes solvent, and the mixture becomes the solution.

Explanation:

Answer:

a solution

Explanation:

solute and solvent(water) put together would produce a solution

A quasar is a star that emits intense radio and light energy.

A quasar is an extremely bright radio source. It is called a quasi-stellar radio source. It appears to be like a star but is not a star. These quasars are young galaxies that are located far away from us and are highly luminous. The luminosity of a quasar is 1000 times greater than the luminosity of a milky way galaxy.

A quasar is powered by a supermassive black hole with its mass ranging from millions to tens of billions of solar masses, surrounded by a gaseous accretion disc.

The quasars were first discovered in the 1950s using the Hubble space telescope and were found to be a massive bright source emitting radio waves of unknown origin. But now, millions of quasars were discovered.

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         The term "total moles of a solute contained in a kilogram of a solvent" is used to describe molality. Molal concentration is another name for molality. It is a measurement of a solution's solute concentration.

  Molarity is a unit of measurement for the concentration of a material in a specific volume of solution (M). The amount of a solute in one liter of solution is known as its molarity. The molarity of a solution is sometimes referred to as its molar concentration.

As a result, we start by assuming that the reaction is finished and that its volume is constant.

The following is the balanced stoichiometric equation:

BaSO4 + 2NH4(CH3COO) = Ba(CH3COO)2 + (NH4)2SO4.

First, we must identify the surplus reactant and the one that the process has entirely consumed.

For Ba(CH3COO)2,

The formula for moles is (Mass/) (Molar Mass)

Mass of barium acetate is 2.68 g.

Molar mass of barium acetate is 255.43 g/mol.

There are 0.0104 moles, or (2.68/255.43), in total.

Number of moles for (NH4)2SO4 = (Concentration in mol/L) (Volume in L)

Ammonium surface concentration in mol/L is 45 M.

(300/1000) x volume in L = 0.3 L

45 divided by 0.3 to equal 13.5 moles.

According to the reaction's stoichiometric balance, 1 mole of Ba(CH3COO)2 produces 1 mole of (NH4)2SO4.

Ba(CH3COO)2 produces 2 moles of NH4(CH3COO) from 1 mole.

Ba(CH3COO)2 will provide 2 0.0591 moles of NH4(CH3COO), or 0.1182 moles of NH4(CH3COO), from 0.0591 moles of Ba(CH3COO)2.

If NH4(CH3COO) has a molarity, give the number of moles. Volume in L

0.1182 moles are the number of moles.

0.3 L is equal to L of the solution.

NH4(CH3COO) has a molarity of (0.01182/0.3) = 0.0394 M.

Consider that 0.0394 M of NH4(CH3COO) likewise contains 0.0394 M of acetate ion because 1 mole of NH4(CH3COO) includes 1 mole of acetate ion.

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Molarity or molar concentration is a measure of the concentration of a chemical species, of a solute in a solution, using as units, number of moles, and volume in liters. The formula for Molarity is:

M = n/V

Where:

n = number of moles

V = volume in Liters, 1 Liter

But we need to find the number of moles, we will do so by using its molar mass, KI = 166g/mol and the given mass in the question, 500g grams

166g = 1 mol

500g = x moles

x = 3.012 moles

Now we can use the Molarity formula

M = 3.012/1

M = 3.012 M, this is the molar concentration of the solution, 2

The elements with the same number of energy levels are the ones that belong to the same period of the periodic table.

Copper and Zinc both belong to the 4th period of the periodic table.

Nickel belongs to the 4th period and palladium to the 5th period.

Lithium belongs to the 2nd period and Magnesium to the 3rd period.

It means that the correct answer is Copper and Zinc, they belong to the same period,

The body of avocado fruit can be compared with the cell structure. The skin of the avocado is relatable with the cell membrane. Thus option B is correct.

Cell is the basic unit of life. Cells connect together to forms  tissues and tissues forms organs and a group organs forms an organ system. These different organ systems buildup the whole body.

Cell contains the core called nucleus. Inside the nucleus genetic material DNA, ribosomes, Golgi apparatus, lysosomes etc are located. The function of cell membrane is to protect the cell from damages as the skin do for our body.

In plants unlike animals, their cell is protected by a cell wall apart from cell membrane and various other differences are there in the cell structure of plant cells.

The fluid filled portion of cell is called cytoplasm. The inner content of the avocado fruit is comparable with the cytoplasm and its seed can be considered as the model for nucleus.

Therefore, the avocado's skin represents the cell membrane. Hence, option B is correct.

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Answer:

0.999

Explanation: divide by 10

Answer

T = 226.21 K

Explanation

Given:

Pressure = 123 kPa

Volume = 10.0 L

number of moles = 0.654 moles

We know R = 8.314 L kPa/mol k.

Required: Temperature

Solution:

Pv = nRT

T = PV/nR

T = (123 kPa x 10.0 L)/(0.654 mol x 8.314 L kPa/mol k)

T = 226.21 K

The balanced equation

2H2 +O2 =====> 2H2O

What is balanced equation ?

An equation for a chemical reaction is said to be balanced if both the reactants and the products have the same number of atoms and total charge for each component of the reaction. In other words, both sides of the reaction have an equal balance of mass and charge.

The balanced equation

2H2 +O2 =====> 2H2O

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The pH of a 0.670 M solution of Ca(NO₂)₂ is 1.76

When HNO₂ dissociates, it forms H⁺ and NO₂⁻ ions.

HNO₂ ==> H⁺ + NO₂⁻

Ka of HNO₂ = [H⁺] [NO₂⁻] / [HNO₂] = 4.5× 10⁻⁴

Let’s take x for unknown

4.5 x 10⁻⁴ = (x)(x) / 0.670

4.5 x 10⁻⁴ = x² / 0.670

x² = 3.015 x 10⁻⁴

x = 1.74 x 10⁻²

[H⁺] = 1.74 x 10⁻² M

pH is the measurement of the acidity or basicity of a compound. It ranges from  0 to 14

Therefore, the pH of a 0.670 M solution of Ca(NO₂)₂ is

pH = -log [H⁺]

pH = -log 1.74 x 10⁻²

pH = 1.76

The pH of a 0.670 M solution of Ca(NO₂)₂ is 1.76 which lies in the acidic range (0 to 7)

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Step 1

The reaction must be completed and balanced:

4NH3 (g) + 9O2 (g) => 4NO3 + 6H2O (g)

Reactants: NH3 and O2

Products: NO3 and H2O

--------------------

Step 2

Information provided:

STP conditions, therefore:

1 mole of gas (NH3 in this case) = 22.4 L (volume)

5.3 g of O2

Liters => L

Grams => g

---------

Information needed:

The molar mass of O2 = 32.0 g/mol

-------------------

Step 3

By stoichiometry,

1 mole NH3 = 22.4 L NH3

1 mole O2 = 32.0 g O2

Procedure: We will work with volume and mass

4NH3 (g) + 9O2 (g) => 4NO3 + 6H2O (g)

4 x 22.4 L NH3 ---------- 9 x 32.0 g O2

X ----------- 5.3 g O2

X = 5.3 g O2 x 4 x 22.4 L NH3/9 x 32.0 g O2 = 1.65 L approx.

Answer: 1.65 L of NH3

The question requires us to explain how a conversion factor must be used in a dimensional analysis expression.

We can say that a conversion factor is a fraction that we use to convert one unit of measure to another (as long as they measure the same quantity), and it conveys the relationship between these units of measure.

When using a conversion factor in a dimensional analysis process, we need to consider it as a "constant" that multiplies the expression of the dimensional analysis (and always with units that refer to the same measurement). We can't use it as a number in an addition or subctration, for example, or use a conversion factor of volume with an unit of distance.

Answer: The answer for 28 A is [tex][He]2s^2 2p^2[/tex]

28 B is [tex]1s^2 2s^2 2p^1[/tex]

We are going to assume that the gas behaves like an ideal gas, so we can apply the following equation:

Where,

P is the pressure of the gas in atm

V is the volume of the gas in liters, 2600mL=2.6L

n is the number of moles

R is a constant, 0.08206atm.L/mol.K

T is the temperature in Kelvin, 33.0°C=306.15K

Now we need to find the moles of O2 to plug into the equation. We divide the grams by the molar mass of O2. The molar mass of O2 is 31.9988g/mol.

We substitute the values in the ideal gas equation:

Now, we convert the atm to mmHg:

Answer: The pressure of the gas is 1033mmHg

Alkali Metals are located in the first group in the periodic table. (Hydrogen is not alkali, be careful with that).

Alkaline Earth Metals are in group number two, right next to the Alkali Metals.

You have to look at the vertical groups ( 1 and 2).

----------------------------------------------------------------------------------------------------------------

ALKALI METALS (AL) VS ALKALINE EARTH METALS (ALE).

Alkali Metals are soft, Alkaline Earth Metals are hard.

AL have only one electron in the last shell, ALE have 2.

AL present a low melting point, ALE high.

AL form hydroxides strongly basic, ALE hydroxides are less basic.

AL are more reactive than ALE

AL have +1 ionic charge in their compounds, ALE have +2 ionic charge in their compounds.

Answer:

eventually, they'll always stop burning - how long that takes depends on the glass size

Explanation:

the candle stops burning once it consumes all the oxygen inside the glass. the bigger the glass, the more oxygen there is, but eventually, even that will run out. so, smaller glass means faster, larger slower.

hope that helps

The valence electrons are very effective in screening the core electrons from the full charge of the nucleus statements about effective nuclear charge is true

The attractive positive charge of nuclear protons acting on valence electrons is known as effective nuclear charge. Due to the shielding effect, the effective nuclear charge is always smaller than the total amount of protons in a nucleus. In comparison to all other periodic table trends, effective nuclear charge lags behind.

Although a fluorine atom's nucleus has a 9-volt charge Z, the core electrons—four from the 1s and 2s orbitals—and some of the 7 electrons in the 2p orbitals—screen the valence electrons noticeably. Therefore, the cation of sodium has the highest effective nuclear charge.

Effective nuclear charge lowers down a group and rises from left to right across a period in the periodic table.

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The question requires us to calculate the amount of moles of water that we would have in 5.3x10^26 molecules of water.

To solve this problem, we'll need to consider the Avogadro Number: this number states the amount of particles (electrons, ions, atoms, molecules etc.) in one mole of a substance. The Avogadro Number corresponds to 6.022 x 10^23 particles per mol.

Considering the Avogadro number and the number of molecules provided by the question, we can write:

6.022 x 10^23 molecules of water -------------------- 1 mol of water

5.3 x 10^26 molecules of water ------------------------ x

Solving for x, we'll have:

Therefore, there are 8.8 x 10^2 moles of water in 5.3 x 10^26 molecules of water.

The relationship between n, ℓ, and the total number of nodes is given by the expression; Number of spherical nodes = n - ℓ - 1.

The number of nodes has to do with the points on the orbital where there is a zero electron density. It is the points along the orbital where there re no electrons. Recall that the orbitals are the regions in space where there is a high probability of finding an electron.

There are various orbitals and the number of nodes of each of the orbitals does vary. The s orbital has no nodes while the p orbital is known to have one node.

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To count atoms, we can find the total sum of the subscripts in a chemical compound.

This is the case for most compounds. In some cases, we will have to multiply subscripts when there are elements inside brackets.

We're given:

Li₂SO₂

In front of lithium (Li), there is a 2.

In front of sulfur (S), there is nothing, which means 1.

In front of oxygen (O), there is a 2.

Add:

2 + 1 + 2 = 5

Therefore, there are 5 atoms in Li₂SO₂.

5 atoms

When copper carbonate disolves the following happens:

The formula for the solubility product constant is:

As for every copper ion in solution there is one carbonate ion, we know that the concentration of both ions in solution is 0.57mol/l.

Now we calculate the constant:

So the answer is Ksp= 0.3249 mol2/L2

In order to solve this question we need to set up the properly balanced equation first:

CaCO3 + 2 HCl -> CaCl2 + H2O + CO2

Now that our reaction is properly balanced, we have to find the limiting reactant in order to find how much mass of CaCl2 will be produced

We have:

10.0 g of CaCO3, molar mass = 100.086 g/mol

15.0 g of HCl, molar mass = 36.46 g/mol

Now we need to find the number of moles of the reactants, and see if the amount available of the other reactant is the one needed to react.

CaCO3:

100.086g = 1 mol

10g = x moles

x = 0.099 moles of CaCO3

According to the molar ratio, the CaCO3 and HCl will have a relationship in which we will always need 2 times more HCl than CaCO3, therefore if we have 0.099 moles of CaCO3, we will need 0.198 moles of HCl in order to proceed with the reaction, but we don't know if that is the right amount, let's check:

HCl:

36.46g = 1 mol

15.0g = x moles

x = 0.411 moles of HCl, this means that we have an excess of HCl, since we only need 0.198 moles in order to react with CaCO3. Therefore Calcium carbonate is the limiting reactant.

Now that we know which one is the limiting reactant, we can find the mass produced of CaCl2.

Again the molar ratio is important here, but know, we will always have the same number of moles for CaCO3 and CaCl2, 1:1 will be the molar ratio, therefore if we have 0.099 moles of CaCO3, we will also have 0.099 moles of CaCl2, using its molar mass, 110.978g/mol, we can find the final mass

CaCl2:

110.978g = 1 mol

x grams = 0.099 moles

x = 11.0 grams (it is actually 10.986 grams, but I have rounded up to 11 grams)

Aluminum Oxide decomposes to Aluminum metal and Oxygen gas.

- First, write down each compound:

- Second, write the number of moles of each compound, so that we have the same amount of reactants as products. Here, it is important not to change the subscript of compound elements.

For example, let's start by adding a number 2 in front of the aluminum metal to balance:

So far, the amount of aluminum has been balanced but the amount of oxygen is unbalanced, so let's add a number 3 for the oxygen gas.

Now, to have the same amount of moles of oxygen on both sides, let's put a number 2 in the aluminum oxide:

Here, the amount of aluminum moles is unbalanced, so we add a number 4 for the aluminum metal to balance:

- This is the final balanced equation of decomposition of aluminum oxide:

The pOH of this solution is 6.2 as pH is 7.80, The hydronium ion concentration is   1.58*10^-8 M, The hydroxide ion concentration is  6.3*10^-7 M

What is pH?
pH is a numerical indicator of how acidic or basic aqueous or other liquid solutions are. The phrase, which is frequently used in chemistry, biology, and agronomy, converts the hydrogen ion concentration, which typically ranges between 1 and 1014 gram-equivalents per litre, into numbers between 0 and 14. The hydrogen ion concentration in pure water, which has a pH of 7, is 107 gram-equivalents per litre, making it neutral (neither acidic nor alkaline). A solution with a pH below 7 is referred to as acidic, and one with a pH over 7 is referred to as basic, or alkaline.

pKw = pH + pOH
14 = 7.80+ pOH
pOH = 14 -7.80 = 6.2

pH = - log [H+]
[H+] = 1.58*10^-8 M

pOH = - log [OH-]
[OH-] = 6.3*10^-7 M

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Na+ (g) --> Na+ (aq) AH = -364 kJmol 1 is endothermic reaction. The given reaction is False, As H is negative hence exothermic reaction not endothermic

What is endothermic  reaction?

Chemical processes referred to as endothermic reactions occur when the reactants take in heat energy from their environment to create products. These reactions produce a cooling effect by bringing the temperature of the space around them down. Ice cubes absorb heat energy from their surroundings and melt to generate liquid water as an example of an endothermic physical process (no chemical bonds are broken or formed).

False, As H is negative hence exothermic reaction not endothermic

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Explanation:

Aluminum will react with chlorine gas according to the following reaction:

2 Al (s) + 3 Cl₂ (g) ----> 2 AlCl₃

We have to find the mass of Cl₂ that will completely react with 13.5 g of Al. First we have to convert the mass of Al to moles using its molar mass.

molar mass of Al = 26.98 g/mol

moles of Al = 13.5 g * 1 mol/(26.98 g)

moles of Al = 0.500 mol

2 Al (s) + 3 Cl₂ (g) ----> 2 AlCl₃

Now, according to the coefficients of the reaction, 2 moles of Al will react with 3 moles of Cl₂. So the molar ratio between them is 2 to 3. We can use that relationship to find the number of Cl₂ that will react with 0.500 mol of Al.

2 mol of Al : 3 moles of Cl₂ molar ratio

moles of Cl₂ = 0.500 mol of Al * 3 moles of Cl₂/(2 moles of Al)

moles of Cl₂ = 0.750 mol

And finally we can convert back to grams using the molar mass of Cl₂.

molar mass of Cl₂ = 70.91 g/mol

mass of Cl₂ = 0.750 moles * 70.91 g/(1 mol)

mass of Cl₂ = 53.2 g

Answer: a. 53.2 g of Cl₂ for complete reaction.

Answer:

right

Explanation: